Fruit to put round a sort of cake (7)
I believe the answer is:
tangelo
'fruit' is the definition.
(I know that tangelo is a type of edible fruit)
'to put round a sort of cake' is the wordplay.
'put round' indicates putting letters inside.
'a sort of cake' becomes 'angel'.
'to' placed around 'angel' is 'TANGELO'.
(Other definitions for tangelo that I've seen before include "Mixed fruit" , "Citrus hybrid - goal net (anag)" , "sharp cross" , "fruitful merger?" , "Hybrid fruit; eat long (anag.)" .)