Female relative has nothing with the Continental breakfast cereal (7)
I believe the answer is:
granola
'breakfast cereal' is the definition.
(I've seen this before)
'female relative has nothing with the continental' is the wordplay.
'female relative' becomes 'gran'.
'has nothing' becomes 'o' (I've seen this in other clues).
'with' is a charade indicator (letters next to each other).
'the continental' becomes 'la' ('the' in French).
'gran'+'o'+'la'='GRANOLA'
(Other definitions for granola that I've seen before include "breakfast dish" , "US breakfast cereal" , "type of cereal" .)