Enticed unfit to embrace exercise bug (9)
I believe the answer is:
centipede
'bug' is the definition.
(thesaurus)
'enticed unfit to embrace exercise' is the wordplay.
'unfit' indicates anagramming the letters.
'to embrace' indicates putting letters inside.
'exercise' becomes 'pe' (Physical Education).
'enticed' anagrammed gives 'centide'.
'centide' enclosing 'pe' is 'CENTIPEDE'.
(Other definitions for centipede that I've seen before include "Creepy type" , "Many-legged invertebrates" , "One crawling" , "Invertebrate with many legs" , "Myriapod" .)