Slob, half cheese, half fat (5)
I believe the answer is:
obese
'fat' is the definition.
(similar in meaning)
'slob half cheese half' is the wordplay.
'half' means to take half the letters.
'half' means to take half the letters.
'slob' cut in half is 'ob'.
'cheese' with half the letters taken is 'ese'.
'ob'+'ese'='OBESE'
(Other definitions for obese that I've seen before include "Extremely overweight" , "getting well-upholstered" , "Abnormally fat" , "in need of slimming down" , "Having excessive girth" .)