Middle of Viennese bonbons, round and plump (5)
I believe the answer is:
obese
'plump' is the definition.
(I've seen this before)
'middle of viennese bonbons round' is the wordplay.
'middle of' indicates the answer is hidden within the clue (the answer is somewhere in the middle of the clue).
'round' is a reversal indicator.
'esebo' is hidden in the letters of 'viennese bonbons'.
'esebo' in reverse letter order is 'OBESE'.
'and' acts as a link.
(Other definitions for obese that I've seen before include "Morbidly overweight" , "round" , "Extremely fat" , "Very big" , "Needing to lose weight" .)