Flames are terribly rife (4)
I believe the answer is:
fire
'flames' is the definition.
(I've seen this in another clue)
'terribly rife' is the wordplay.
'terribly' indicates anagramming the letters.
'rife' with letters rearranged gives 'FIRE'.
'are' acts as a link.
(Other definitions for fire that I've seen before include "See 5" , "Trigger" , "Flame - dismiss - shoot" , "Shoot; sack" , "Weaponry" .)