Fat? Radical to suppress pounds (4)
I believe the answer is:
flab
'fat?' is the definition.
(flab is a kind of fat)
'radical to suppress pounds' is the wordplay.
'radical' becomes 'fab' (both can informally mean good).
'to suppress' indicates putting letters inside.
'pounds' becomes 'l' (L can represent the monetary pound).
'fab' placed around 'l' is 'FLAB'.
(Other definitions for flab that I've seen before include "Soft loose flesh" , "Unwanted body fat" , "Loose body fat" , "Excess body fat" , "spare tyre?" .)