Group of animals caught it’s said (4)
I believe the answer is:
herd
'group of animals' is the definition.
(I've seen this before)
'caught it's said' is the wordplay.
'caught' becomes 'heard' (I've seen this before).
'it's said' shows a homophone (sound like).
'heard' is a homophone of 'HERD'.
(Other definitions for herd that I've seen before include "Large group of animals" , "Host" , "Group of people behaving like sheep?" , "Bunch of cattle" , "13 Down group" .)