Might possibly (3)
I believe the answer is:
may
'might possibly' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for may that I've seen before include "Hawthorn blossom" , "The permissive month" , "UK PM" , "Girl's name; 10 ac (anag.)" , "'5 _____' (popular piece of music by Bach)" .)