Except for upsetting pieces on animals (7)
I believe the answer is:
rabbits
'animals' is the definition.
The answer is an example.
'except for upsetting pieces on' is the wordplay.
'except for' becomes 'bar' (I've seen this before).
'upsetting' is a reversal indicator.
'pieces' becomes 'bits' ('bit' can be a synonym of 'piece'**).
'on' says to put letters next to each other.
'bar' in reverse letter order is 'rab'.
'rab'+'bits'='RABBITS'
(Other definitions for rabbits that I've seen before include "timid people" , "Watership Down protagonists" , "Warren residents" , "Poor batsmen; chatters" , "poor players" .)