Filling for chocolates — plainer sorts (7)
I believe the answer is:
praline
'filling for chocolates' is the definition.
(I've seen this before)
'plainer sorts' is the wordplay.
'sorts' indicates an anagram (I've seen 'sorted' mean this).
'plainer' anagrammed gives 'PRALINE'.
(Other definitions for praline that I've seen before include "Plainer (anag.)" , "Sweet stuff" , "Smooth nut filling" , "Chocolate filling of nuts and sugar" , "Confection made with crushed nuts" .)