Member of parliament opposed women's lib initially (3)
I believe the answer is:
owl
'member of parliament' is the definition.
('parliament' is the collective noun for 'owl')
'opposed women's lib initially' is the wordplay.
'initially' suggests taking the first letters.
The initial letters of 'opposed womens lib' is 'OWL'.
(Other definitions for owl that I've seen before include "Bird of the 18" , "Smuggle sheep" , "Member of Parliament" , "Harry Potter's Hedwig, for instance" , "Pussy-cat's wooer (Lear)" .)