Sweet is mine reportedly (5)
I believe the answer is:
bombe
'sweet' is the definition.
(type of dessert or sweet)
'mine reportedly' is the wordplay.
'mine' becomes 'bomb' (I've seen this before).
'reportedly' becomes 'e' (I've seen this in other clues).
'bomb'+'e'='BOMBE'
'is' is the link.
(Other definitions for bombe that I've seen before include "Ice-cream dessert" , "like some rounded furniture" , "Sweet" , "Ice cream frozen in a round mould" , "Dome-shaped dessert, often frozen" .)