Fat Duck cooks bees! (5)
I believe the answer is:
obese
'fat' is the definition.
('obese' can be similar in meaning to 'fat')
'duck cooks bees' is the wordplay.
'duck' becomes 'o'.
'cooks' indicates an anagram.
'bees' anagrammed gives 'bese'.
'o'+'bese'='OBESE'
(Other definitions for obese that I've seen before include "Falstaffian" , "porky?" , "Morbidly overweight" , "Clinically overweight" , "Unusually fat" .)