Sweet plum filled with cream, originally (4,3)
I believe the answer is:
choc ice
'sweet' is the definition.
(choc ice is a type of sweet)
'plum filled with cream originally' is the wordplay.
'plum' becomes 'choice' (I've seen this before).
'filled with' is an insertion indicator.
'originally' suggests taking the first letters.
The first letter of 'cream' is 'c'.
'choice' placed around 'c' is 'CHOC-ICE'.
(Other definitions for choc ice that I've seen before include "dessert" , "Something to eat" , "Usherette may offer this" , "Sweet" , "Cold, coated confection" .)