Little devil has a conclusion that it's imminent (9)
I believe the answer is:
impending
'it's imminent' is the definition.
(synonyms)
'little devil has a conclusion' is the wordplay.
'little devil' becomes 'imp' (an imp is a little demon).
'has' means one lot of letters go next to another.
'a conclusion' becomes 'ending' ('ending' can be a synonym of 'conclusion').
'imp'+'ending'='IMPENDING'
'that' acts as a link.
(Other definitions for impending that I've seen before include "coming?" , "About to happen" , "Looming" , "Threatening" .)