Syrup and cereal stirred at temperature (7)
I believe the answer is:
treacle
'syrup' is the definition.
(treacle is a kind of syrup)
'cereal stirred at temperature' is the wordplay.
'stirred' indicates anagramming the letters.
'at' means one lot of letters go next to another (I've seen this in other clues).
'temperature' becomes 't' (abbreviation).
'cereal' with letters rearranged gives 'reacle'.
'reacle' put after 't' is 'TREACLE'.
'and' acts as a link.
(Other definitions for treacle that I've seen before include "Something cloyingly sweet" , "Saplike stuff" , "Syrup-like substance" , "refined product" , "Electra (anag)" .)