Punch with a couple of slices of bread? (7,8)
I believe the answer is:
knuckle sandwich
'bread?' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'punch with a couple of slices' is the wordplay.
'punch with' becomes 'knuckle' (I can't explain this - if you can you should give a lot more credence to this answer).
'a couple of slices' becomes 'sandwich'.
'knuckle'+'sandwich'='KNUCKLE SANDWICH'
'of' acts as a link.
(Other definitions for knuckle sandwich that I've seen before include "Buffet" , "piece of pork between slices of bread" , "Bunch of fives" , "Slug" , "hit" .)