Hindu spiritual and ascetic discipline (4)
I believe the answer is:
yoga
'hindu spiritual and ascetic discipline' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for yoga that I've seen before include "Hindu ascetic system" , "Hindu physical and mental exercises" , "Hindu philosophy of tranquility through physical exercise" , "(Hindu) mind and body toning" , "exercise regime" .)