Group interrupting quiet animal (5)
I believe the answer is:
sloth
'animal' is the definition.
(I know that sloth is a type of edentate)
'group interrupting quiet' is the wordplay.
'group' becomes 'lot'.
'interrupting' is an insertion indicator.
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'lot' placed inside 'sh' is 'SLOTH'.
(Other definitions for sloth that I've seen before include "One of the seven deadly sins" , "Inertia" , "edentate" , "Jungle mammal; laziness" , "Sluggish creature" .)