In Patanjali Yoga-Sutras the word Dharana is used to denote mindfulness or chitt ekagrata as desired by you - Mindedness with proper practice and Idol Worship Patanjali is defining this phenomena as.
देशबन्धः चित्तस्य धारणा ॥1॥
deśa-bandhaḥ cittasya dhāraṇā || Yoga Sutras 3.1 ||
Concentration (dharana) is holding the mind within a center of
spiritual consciousness in the body, or fixing it on some divine form,
either within the body or outside it.
3.1 Concentration (dharana) is the process of holding or fixing the attention of mind onto one object or place, and is the sixth of the eight rungs. (deshah bandhah chittasya dharana)
In order to achieve this concentration, we must calm and purify our minds. Patañjali now tells us how to do this. He prescribes the mental attitude we should take toward our neighbours in this world.
मैत्री करुणा मुदितोपेक्षाणांसुखदुःख पुण्यापुण्यविषयाणां भावनातः
maitrī karuṇā mudito-pekṣāṇāṃ-sukha-duḥkha puṇya-apuṇya-viṣayāṇāṃ
bhāvanātaḥ citta-prasādanam ||Yoga Sutras 1.33||
Undisturbed calmness of mind is attained by cultivating friendliness
toward the happy, compassion for the unhappy, delight in the virtuous,
and indifference toward the wicked.
Concentration (3.1) comes from attention and means that the attention is focused on one object, though the concentration may be interrupted, and is thus temporary. There is still an observer, who is doing the process of observing, and an object that is being observed.
The centers of spiritual consciousness here referred to are the seven lotuses (II, 49-50). In order to concentrate, you must first fix your mind upon the Inner Light within one of these lotuses, as your teacher directs. Or you may concentrate upon the form of your Chosen Ideal, trying to visualize that form either within a lotus or outside your own body altogether.
Now here Patanjali is telling us about another kind of concentration ,where there are no thoughts in mind , or consciousness contains no object. This can be achieved through non attachment and practicing not to let any thought wave getting being generate in our mind constantly.
विरामप्रत्ययाभ्यासपूर्वः संस्कारशेषोऽन्यः ॥ Yoga Sutras
virāma-pratyaya-abhyāsa-pūrvaḥ saṃskāra-śeṣo-'nyaḥ ||18||
The other kind of concentration is that 'in which the consciousness
contains no object—only subconscious impressions, which are like burnt
seeds. It is attained by constantly checking the thought-waves through
the practice of non-attachment.
And here is the brief procedure.
3.1 comes from attention and means that the attention is focused on one object, though the concentration may be interrupted, and is thus
temporary. There is still an observer, who is doing the process of
observing, and an object that is being observed.
After sitting in either Padmasana (lotus position) or any other Asana,
and after concentrating the sight to the tip of the nose and after
controlling both the hands and legs, meditate on the letter ‘Aum’ with
a concentrated mind. If one continuously meditates on Parameshwara,
If we sit in an asana and continuously practice, the bindu will cease
from going down. Without Pooraka and Rechaka, the Prana would stand in
Kumbhaka for a very long time. You would hear different types of
sound. The nectar will start flowing from the place of the moon.
Hunger and thirst will cease. Mind would get concentrated on the ever
flowing bliss. The four steps for this are Mantra Yoga, Laya Yoga,
Hatha Yoga and Raja Yoga.