Last bit of breakfast cereal, nuts, syrup (7)
I believe the answer is:
treacle
'syrup' is the definition.
(I know that treacle is a type of syrup)
'last bit of breakfast cereal nuts' is the wordplay.
'last bit of' says to take the final letters.
'nuts' indicates an anagram (nuts can mean crazy).
The final letter of 'breakfast' is 't'.
'cereal' with letters rearranged gives 'reacle'.
't'+'reacle'='TREACLE'
(Other definitions for treacle that I've seen before include "Something sticky" , "Sticky fluid" , "flattery" , "Carroll's sisters had to live with" , "Electra (anag)" .)