Eat briefly, making racket (3)
I believe the answer is:
din
'racket' is the definition.
(I've seen this before)
'eat briefly' is the wordplay.
'eat' becomes 'dine' (to dine is to eat a meal).
'briefly' means to remove the last letter.
'dine' with its last letter taken away is 'DIN'.
'making' acts as a link.
(Other definitions for din that I've seen before include "Loud unpleasant noise" , "Loud noise, racket" , "Hubbub" , "speed in film" , "Distracting noise" .)