Comply, accepting its strange corpulence (7)
I believe the answer is:
obesity
'corpulence' is the definition.
(I know that corpulence can be written as obesity)
'comply accepting its strange' is the wordplay.
'comply' becomes 'obey' (I've seen this before).
'accepting' indicates putting letters inside (inserted letters are accepted).
'strange' indicates an anagram.
'its' with letters rearranged gives 'sit'.
'obey' enclosing 'sit' is 'OBESITY'.
(Other definitions for obesity that I've seen before include "health issue" , "Abnormal fatness" , "Gross fatness" , "Bulk" , "State of being unhealthily fat" .)