Fat means nothing to wild bees (5)
I believe the answer is:
obese
'fat' is the definition.
('obese' can be similar in meaning to 'fat')
'nothing to wild bees' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'to wild' is an anagram indicator.
'bees' anagrammed gives 'bese'.
'o'+'bese'='OBESE'
'means' acts as a link.
(Other definitions for obese that I've seen before include "Grossly overweight" , "Extremely overweight" , "Morbidly fat" , "Abnormally fat" , "Stout" .)