Jenny, say, cutting duets in jazzy solo (10)
I believe the answer is:
unassisted
'solo' is the definition.
(I've seen this before)
'jenny say cutting duets in jazzy' is the wordplay.
'jenny say' becomes 'ass' (jenny is a female ass).
'cutting' means one lot of letters goes inside another (some letters cut their way into a word).
'jazzy' indicates anagramming the letters.
'duets'+'in'='duetsin'
'duetsin' is an anagram of 'unisted'.
'ass' inserted inside 'unisted' is 'UNASSISTED'.
(Other definitions for unassisted that I've seen before include "Without help" , "Solo" , "Getting no help" .)