Stroppy vegetarian with tum rumbling (13)
I believe the answer is:
argumentative
'stroppy' is the definition.
(stroppy means bad-tempered)
'vegetarian with tum rumbling' is the wordplay.
'with' means one lot of letters go next to another.
'rumbling' is an anagram indicator (I've seen this in other clues).
'vegetarian'+'tum'='vegetariantum'
'vegetariantum' anagrammed gives 'ARGUMENTATIVE'.
(Other definitions for argumentative that I've seen before include "Quarrelsome" , "Contentious" , "stroppy" , "Given to disputation" , "keen on rowing" .)