Suddha-cetasah means
Srimad-Bhagavatam
SB Canto 3
Persons who work at their prescribed duties, not for sense gratification but for gratification of the Supreme Lord, are called niḥsaṅga, freed from the influence of the modes of material nature. Nyasta-karmāṇaḥ indicates that the results of their activities are given to the Supreme Personality of Godhead. Such persons appear to be acting on the platform of their respective duties, but such activities are not performed for personal sense gratification; rather, they are performed for the Supreme Person. Such devotees are called praśāntāḥ, which means "completely satisfied." Śuddha-cetasaḥ means Kṛṣṇa conscious; their consciousness has become purified. In unpurified consciousness one thinks of himself as the Lord of the universe, but in purified consciousness one thinks himself the eternal servant of the Supreme Personality of Godhead. Putting oneself in that position of eternal servitorship to the Supreme Lord and working for Him perpetually, one actually becomes completely satisfied. As long as one works for his personal sense gratification, he will always be full of anxiety. That is the difference between ordinary consciousness and Kṛṣṇa consciousness.