A recipe I cooked up, topped with hot syrup (9)
I believe the answer is:
hairpiece
'syrup' is the definition.
('syrup of fig' is Cockney rhyming slang for 'wig')
'a recipe i cooked up topped with hot' is the wordplay.
'cooked up' indicates anagramming the letters.
'topped with' means one lot of letters go next to another.
'hot' becomes 'h'.
'recipe'+'i'='recipei'
'recipei' anagrammed gives 'irpiece'.
'a'+'irpiece'='airpiece'
'airpiece' put after 'h' is 'HAIRPIECE'.
(Other definitions for hairpiece that I've seen before include "A wig or switch to supplement scalp covering" , "Using switch" , "False addition to existing growth on the head" , "rug" , "Switch, for instance" .)