American brought up his poorly prepared food (5)
I believe the answer is:
sushi
'prepared food' is the definition.
'sushi' can be an answer for 'food' (sushi is a kind of food). I am unsure of the 'prepared' bit.
'american brought up his poorly' is the wordplay.
'american' becomes 'US' (abbreviation for United States).
'brought up' shows that the letters should be reversed in order (in a down clue, letters go up).
'poorly' indicates an anagram (a poor spelling).
'us' written backwards gives 'su'.
'his' is an anagram of 'shi'.
'su'+'shi'='SUSHI'
Can you help me to learn more?
(Other definitions for sushi that I've seen before include "cold food" , "oriental dish" , "Exotic food" , "Japanese cuisine" , "Japanese rice and raw fish dish" .)