Indicate hidden animal (3)
I believe the answer is:
cat
'animal' is the definition.
(I've seen this before)
'indicate hidden' is the wordplay.
'hidden' indicates a hidden word.
'CAT' is hidden in the letters of 'indicate'.
(Other definitions for cat that I've seen before include "Lash < jazz fan" , "Eg, tiger, lion" , "Animal (domesticated or wild)" , "Malicious gossip" , "eg Leopard" .)