Punch, having belted out tune the wrong way (7)
I believe the answer is:
sangria
'punch' is the definition.
(I've seen this before)
'belted out tune the wrong way' is the wordplay.
'belted out' becomes 'sang' (I've seen this in another clue).
'tune' becomes 'air' (air can mean a piece of music).
'the wrong way' is a reversal indicator.
'air' written backwards gives 'ria'.
'sang'+'ria'='SANGRIA'
'having' is the link.
(Other definitions for sangria that I've seen before include "Spanish drink of red wine and spices" , "Spanish drink of red wine, sugar and fruit" , "Red wine, fruit juice, sugar and spices" , "Spanish drink of red wine with soda water or lemonade" , "Spanish drink of wine, lemonade, fruit, etc" .)