Fat man's folds (5)
I believe the answer is:
tucks
'folds' is the definition.
(tucking is a kind of folding)
'fat man's' is the wordplay.
'fat' becomes 'tuc' (I can't justify this - if you can you should believe this answer much more).
'man's' becomes 'k's' (abbreviation for king, a chess man).
'tuc'+'ks'='TUCKS'
(Other definitions for tucks that I've seen before include "stitches" , "Folds" .)