Child brought up on hot food (4)
I believe the answer is:
nosh
'food' is the definition.
(nosh is a kind of food)
'child brought up on hot' is the wordplay.
'child' becomes 'son' (son is a kind of child**).
'brought up' says the letters should be written in reverse (down clues only).
'on' means one lot of letters go next to another.
'hot' becomes 'h'.
'son' written backwards gives 'nos'.
'nos'+'h'='NOSH'
(Other definitions for nosh that I've seen before include "Eat (sl.)" , "A slang meal" , "cuisine" , "Eats" , "Food - eat greedily" .)