Incantation contributing to human transformation (6)
I believe the answer is:
mantra
'incantation' is the definition.
(a mantra is a spiritual incantation)
'contributing to human transformation' is the wordplay.
'contributing to' says the answer is hidden in the clue (the answer contributes to part of the clue ).
'MANTRA' can be found hidden inside 'human transformation'.
(Other definitions for mantra that I've seen before include "Word repeated as aid to concentration during meditation" , "Word aiding meditation (Buddhism)" , "Powerful words" , "Phrase repeated as aid to meditation in Buddhism" , "Repetitive sacred utterance" .)