Mal is a silly sausage (6)
I believe the answer is:
salami
'sausage' is the definition.
(I know that salami is a type of sausage)
'mal is a silly' is the wordplay.
'silly' indicates anagramming the letters.
'mal'+'is'+'a'='malisa'
'malisa' anagrammed gives 'SALAMI'.
(Other definitions for salami that I've seen before include "Banger" , "Highly spiced sausage" , "Cured meat" , "Highly-spiced sausage" , "Highly-seasonal sausage" .)