In need of a muffler (5)
I believe the answer is:
noisy
'in need of a muffler' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for noisy that I've seen before include "ear-piercing maybe!" , "row" , "Loud, rackety" , "Rowdy" , "like thirteen [HARD ROCK]" .)