It may be smoked as cheese roll's topping (5)
I believe the answer is:
brier
'it may be smoked' is the definition.
(I've seen this before)
'cheese roll's topping' is the wordplay.
'cheese' becomes 'brie' (Brie is an example).
'roll's topping' becomes 'r' (I can't justify this - if you can you should believe this answer much more).
'brie'+'r'='BRIER'
'as' is the link.
Can you help me to learn more?
(Other definitions for brier that I've seen before include "Prickly shrub" , "plant" , "smoking pipe" , "Thorny bush like the wild rose" , "It may be smoked" .)