... a counterfeit, inspiring competitor's final retreat (6)
I believe the answer is:
ashram
'retreat' is the definition.
(type of religious retreat)
'a counterfeit inspiring competitor's final' is the wordplay.
'counterfeit' becomes 'sham' (similar in meaning).
'inspiring' indicates putting letters inside.
'final' suggests the final letters.
The last letter of 'competitor' is 'r'.
'sham' going around 'r' is 'shram'.
'a'+'shram'='ASHRAM'
(Other definitions for ashram that I've seen before include "Commune" , "religious community" , "holy man's retreat" , "Hindu hermitage" , "Guru's community" .)