Round bees, awfully overweight (5)
I believe the answer is:
obese
'overweight' is the definition.
(I've seen this before)
'round bees awfully' is the wordplay.
'round' becomes 'o' (round can mean a round object).
'awfully' indicates an anagram.
'bees' with letters rearranged gives 'bese'.
'o'+'bese'='OBESE'
(Other definitions for obese that I've seen before include "Extremely overweight" , "likely to tip the balance?" , "Dangerously corpulent" , "Enormously portly" , "More than podgy" .)