Hunk from poster put on weight (3)
I believe the answer is:
wad
'hunk' is the definition.
(thesaurus)
'poster put on weight' is the wordplay.
'poster' becomes 'ad' (short for advert).
'put on' says to put letters next to each other.
'weight' becomes 'w' (short for weight).
'ad' after 'w' is 'WAD'.
'from' acts as a link.
(Other definitions for wad that I've seen before include "A bundle as of documents or banknotes" , "Compact mass" , "A thick bundle, maybe of money" , "Bundle of soft material or of banknotes" , "Small mass of soft material" .)