Hollow animal home, sett abandoned by group (4)
I believe the answer is:
dent
'hollow' is the definition.
(both can mean an impression or indentation)
'animal home sett abandoned by group' is the wordplay.
'animal home' becomes 'den' (I've seen this in another clue).
'abandoned by' indicates named letters should be taken away.
'group' becomes 'set' (both can mean a collection).
'sett' with 'set' taken away is 't'.
'den'+'t'='DENT'
(Other definitions for dent that I've seen before include "Tend to make small depression" , "Injury to pride" , "A cavity" , "Hollow caused by a blow" , "Slight damage" .)