Menageries (4)
I believe the answer is:
zoos
'menageries' is the definition.
('zoo' can be a synonym of 'menagerie')
This is all the clue.
(Other definitions for zoos that I've seen before include "Whipsnade and Regent's Park" , "Animal displays" , "Exhibitions" , "Menageries" , "Exhibition spaces for wild animals" .)