Madonna's ex (4)
I believe the answer is:
sean
'madonna's ex' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sean that I've seen before include "Penn, Bean or O'Casey" , "guy at Number 10 [IRISHMAN]" , "- - Connery (007)" , "Irish form of John" .)