Design on icy centre of sweets (13)
I believe the answer is:
confectionery
'sweets' is the definition.
(thesaurus)
'design on icy centre of' is the wordplay.
'design' indicates anagramming the letters.
'on'+'icy'+'centre'+'of'='onicycentreof'
'onicycentreof' with letters rearranged gives 'CONFECTIONERY'.
(Other definitions for confectionery that I've seen before include "Sweets, chocolate etc" , "Certify on cone (anag)" , "Sweets, chocolates, etc" , "sweet things" , "Sugary stuff" .)