Word or sound to aid meditation (6)
I believe the answer is:
mantra
'word or sound to aid meditation' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for mantra that I've seen before include "Prayer" , "Sound repeated as an aid to meditation" , "Buddhist aid to concentration" , "oft repeated stock phrase?" , "Incantation used as aid to meditation" .)