Becoming popular again, vital following short break (9)
I believe the answer is:
resurgent
'becoming popular again' is the definition.
'vital following short break' is the wordplay.
'vital' becomes 'urgent'.
'following' is a charade indicator (letters next to each other).
'short break' becomes 'res' (I've seen this in other clues).
'urgent' after 'res' is 'RESURGENT'.
(Other definitions for resurgent that I've seen before include "Reviving after period of inactivity" , "rising again" , "given new life" , "Reviving in popularity" , "Coming back to life" .)