A quiet sheep in retreat (6)
I believe the answer is:
ashram
'retreat' is the definition.
(type of religious retreat)
'a quiet sheep' is the wordplay.
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'sheep' becomes 'ram' (male sheep).
'a'+'sh'+'ram'='ASHRAM'
'in' is the link.
(Other definitions for ashram that I've seen before include "religious community" , "holy man's retreat" , "Hindu retreat location" , "spiritual centre?" , "Hindu retreat house" .)