Sushi topper
I believe the answer is:
roe
'sushi topper' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for roe that I've seen before include "Mass of fish eggs" , "Fish eggs; small deer" , "eg Caviare" , "Hoofed animal(s)" , "Lobster's ripe ovary" .)