Cook disturbed by a brawl (4)
I believe the answer is:
fray
'brawl' is the definition.
(I've seen this in another clue)
'cook disturbed by a' is the wordplay.
'cook' becomes 'fry' (frying is a type of cooking).
'disturbed by' is an insertion indicator (inserted letters disrupt or disturb the word).
'fry' going around 'a' is 'FRAY'.
(Other definitions for fray that I've seen before include "Noisy fight" , "Suffer peripheral damage" , "Unravel at the edges" , "Show effects of strain" , "Conflict; wear at edges" .)