. . . breakfast item for one? Good (3)
I believe the answer is:
egg
'breakfast item' is the definition.
(I've seen this in another clue)
'for one? good' is the wordplay.
'for one?' becomes 'eg' (both can mean 'for example').
'good' becomes 'g' (abbreviation).
'eg'+'g'='EGG'
(Other definitions for egg that I've seen before include "It, or chicken, first?" , "One beaten by a whisker perhaps" , "explosive" , "Breakfast food, perhaps" , "Source" .)