Sweet I stuff into tailored suit (8)
I believe the answer is:
tiramisu
'sweet' is the definition.
(type of dessert or sweet)
'i stuff into tailored suit' is the wordplay.
'stuff' becomes 'ram' (ram can mean to stuff or push).
'into' is an insertion indicator.
'tailored' indicates anagramming the letters (the letters are customised ).
'i'+'ram'='iram'
'suit' with letters rearranged gives 'tisu'.
'iram' put into 'tisu' is 'TIRAMISU'.
(Other definitions for tiramisu that I've seen before include "Greek dessert" , "Dessert -- is it arum? (anag)" , "Italian dessert with coffee and liqueur" , "for which damp sponge is needed" , "Italian sponge dessert" .)