Pork unpopular, but stuff oneself (3,3)
I believe the answer is:
pig out
'stuff oneself' is the definition.
(I've seen this in another clue)
'pork unpopular' is the wordplay.
'pork' becomes 'pig'.
'unpopular' becomes 'out' (similar in meaning).
'pig'+'out'='PIG OUT'
'but' is the link.
(Other definitions for pig out that I've seen before include "gorge" , "To eat a lot may" , "Eat too much food" , "feast" , "overindulge" .)