Yearn for wife to join worker (4)
I believe the answer is:
want
'yearn' is the definition.
(thesaurus)
'wife to join worker' is the wordplay.
'wife' becomes 'w'.
'to join' is a charade indicator (letters next to each other).
'worker' becomes 'ant' (worker is a type of ant).
'w'+'ant'='WANT'
'for' acts as a link.
(Other definitions for want that I've seen before include "Desire to possess" , "'Wilful waste makes woeful . . . .'" , "Crave" , "Wish" , "Need or desire" .)