Marsha shot in retreat (6)
I believe the answer is:
ashram
'retreat' is the definition.
(type of religious retreat)
'marsha shot' is the wordplay.
'shot' is an anagram indicator.
'marsha' with letters rearranged gives 'ASHRAM'.
'in' is the link.
(Other definitions for ashram that I've seen before include "Hindu hermitage" , "Hindu religious retreat" , "Retreat -- a marsh (anag)" , "religious community" , "Indian religious retreat" .)