Not bad after morning in a frenzy (4)
I believe the answer is:
amok
'in a frenzy' is the definition.
(I've seen this in another clue)
'not bad after morning' is the wordplay.
'not bad' becomes 'ok'.
'after' says to put letters next to each other.
'morning' becomes 'am' (as in 12:00 AM).
'ok' put after 'am' is 'AMOK'.
(Other definitions for amok that I've seen before include "A state of murderous frenzy" , "Wild and uncontrollable" , "Run (disruptively out of control)" , "Must run it" , "(Run) in murderous frenzy" .)