Jumper lifted up in error is clumsy (7)
I believe the answer is:
boorish
'clumsy' is the definition.
(thesaurus)
'jumper lifted up in error' is the wordplay.
'jumper' becomes 'roo' (I've seen this before).
'lifted up' says the letters should be written in reverse (in a down clue, letters go up).
'in' indicates putting letters inside.
'error' becomes 'bish' (term for a blunder or mistake).
'roo' back-to-front is 'oor'.
'oor' inserted into 'bish' is 'BOORISH'.
'is' is the link.
(Other definitions for boorish that I've seen before include "Coarse - ill-mannered" , "Rude - vulgar - rustic" , "Coarse, rough or rude" , "Awkward or rude" , "Uncouth" .)