Sound a bit of a chump? (3)
I believe the answer is:
hum
'sound' is the definition.
(I know that hum is a more specific form of the action sound)
'a bit of a chump?' is the wordplay.
'a bit of' indicates a hidden word.
'HUM' is hidden in the letters of 'chump'.
(Other definitions for hum that I've seen before include "Smell strongly" , "Smell badly (slang)" , "Reek" , "Make musical sound with closed lips" , "Make music through closed lips" .)