Sacred word (6)
I believe the answer is:
mantra
'sacred word' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for mantra that I've seen before include "oft repeated stock phrase?" , "Word aiding meditation (Buddhism)" , "Aid to concentration (Buddhism,Hinduism)" , "Oft-repeated slogan or phrase" , "Incantation used as aid to meditation" .)