Marry and look after prince (4)
I believe the answer is:
pair
'marry' is the definition.
(thesaurus)
'look after prince' is the wordplay.
'look' becomes 'air' (something might have a certain air or look).
'after' is a charade indicator (letters next to each other).
'prince' becomes 'p' (abbreviation).
'air' after 'p' is 'PAIR'.
'and' is the link.
(Other definitions for pair that I've seen before include "Two of a similar type" , "Couple - wed" , "2" , "Twosome" , "Husband and wife" .)