Set up a kitchen, back section is ruined (5)
I believe the answer is:
kaput
'is ruined' is the definition.
(I've seen this before)
'set up a kitchen back section' is the wordplay.
'section' indicates a hidden word.
'back' says the letters should be written in reverse.
'tupak' is hidden in the letters of 'set up a kitchen'.
'tupak' in reverse letter order is 'KAPUT'.
(Other definitions for kaput that I've seen before include "Up the spout" , "No longer functioning" , "Bust" , "Defunct (informal)" , "Broken, put out of use" .)