Wilful greedy guts was in charge (9)
I believe the answer is:
pigheaded
'wilful' is the definition.
(pigheaded can mean wilful or stubborn)
'greedy guts was in charge' is the wordplay.
'greedy guts' becomes 'pig' (both can mean a greedy person).
'was in charge' becomes 'headed' (to head something is to be in charge of it).
'pig'+'headed'='PIGHEADED'
(Other definitions for pigheaded that I've seen before include "Extremely obstinate" , "Stubborn" .)