A canny one turning into a nuisance (9)
I believe the answer is:
annoyance
'a nuisance' is the definition.
('annoyance' can be a synonym of 'nuisance')
'a canny one turning' is the wordplay.
'turning' indicates an anagram.
'canny'+'one'='cannyone'
'cannyone' is an anagram of 'nnoyance'.
'a'+'nnoyance'='ANNOYANCE'
'into' acts as a link.
(Other definitions for annoyance that I've seen before include "(Anger at) harassment" , "trouble" , "Feeling of slight anger" , "Source of anger" , "pest" .)