Animal environment where volunteers wear special clothing? (7)
I believe the answer is:
habitat
'animal environment' is the definition.
(natural habitat)
'volunteers wear special clothing?' is the wordplay.
'volunteers' becomes 'TA' (abbreviation for Territorial Army).
'wear' indicates putting letters inside (to wear something is to be covered up by it).
'special clothing?' becomes 'habit' (clothing worn by a monk or nun).
'ta' placed inside 'habit' is 'HABITAT'.
'where' is the link.
(Other definitions for habitat that I've seen before include "Shop founded by Terence Conran" , "Living area" , "Usual abode" , "Surrender" , "Animal's environment" .)