Weightlifter's bane (4)
I believe the answer is:
flab
'weightlifter's bane' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for flab that I've seen before include "Soft loose flesh" , "Informally, unsightly fat" , "spare tyre?" , "Loose body fat" , "Sign of overeating" .)