Fancy leaving wife for social worker? (3)
I believe the answer is:
'social worker?' is the definition.
(I've seen this before)
'fancy leaving wife' is the wordplay.
'fancy' becomes 'want' (both can mean to desire).
'leaving' suggests deleting specific letters.
'wife' becomes 'w' (abbreviation).
'want' with 'w' taken away is 'ANT'.
'for' acts as a link.
(Other definitions for ant that I've seen before include "that may be a soldier" , "One working hard" , "Small social insect" , "Industrious insect" , "Proverbially hard-working insect" .)