Stubborn old boys can have had a meal (9)
I believe the answer is:
obstinate
'stubborn' is the definition.
('obstinate' can be a synonym of 'stubborn')
'old boys can have had a meal' is the wordplay.
'old boys' becomes 'obs' (I've seen this in other clues).
'can' becomes 'tin' ('tin' can be a synonym of 'can').
'have' means one lot of letters go next to another.
'had a meal' becomes 'ate'.
'obs'+'tin'+'ate'='OBSTINATE'
(Other definitions for obstinate that I've seen before include "Stubborn or unyielding" , "Female bird" , "Stubborn, obdurate" , "Blindly stubborn" , "Inflexible" .)