Extra pound in benefit for ham (8)
I believe the answer is:
overplay
'ham' is the definition.
('overplay' can be a synonym of 'ham')
'extra pound in benefit' is the wordplay.
'extra' becomes 'over'.
'pound' becomes 'l'.
'in' indicates putting letters inside.
'benefit' becomes 'pay'.
'l' placed inside 'pay' is 'play'.
'over'+'play'='OVERPLAY'
'for' is the link.
(Other definitions for overplay that I've seen before include "Complicate or exaggerate (something)" , "Give excess emphasis to" , "Embroider" , "Exaggerate the importance of" .)