Admit to rage after midnight (5)
I believe the answer is:
grant
'admit' is the definition.
(thesaurus)
'rage after midnight' is the wordplay.
'rage' becomes 'rant' ().
'after' is a charade indicator (letters next to each other).
'midnight' becomes 'g' (the middle letter in 'night').
'rant' after 'g' is 'GRANT'.
'to' acts as a link.
(Other definitions for grant that I've seen before include "former president" , "Allow; agree to" , "support for education" , "Permit" , "Present" .)