Nice hot food the silly girl left (5)
I believe the answer is:
grill
'nice hot food' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'the silly girl left' is the wordplay.
'the silly' indicates anagramming the letters.
'left' becomes 'L' (common abbreviation).
'girl' with letters rearranged gives 'gril'.
'gril'+'l'='GRILL'
Can you help me to learn more?
(Other definitions for grill that I've seen before include "Grating" , "Framework of metal bars" , "Cook by radiant heat" , "Question closely" , "pump" .)