Refuse to eat hot buffet (6)
I believe the answer is:
thrash
'buffet' is the definition.
(thesaurus)
'refuse to eat hot' is the wordplay.
'refuse' becomes 'trash' (I've seen this before).
'to eat' means one lot of letters goes inside another.
'hot' becomes 'h' (abbreviation eg on taps).
'trash' enclosing 'h' is 'THRASH'.
(Other definitions for thrash that I've seen before include "Beat heavily, perhaps with whip" , "Beat violently" , "tan" , "Administer sound beating to" , "Beat; party (colloq.)" .)