Rewriting duet with lyric displaying naivety (9)
I believe the answer is:
credulity
'naivety' is the definition.
(I've seen this before)
'rewriting duet with lyric' is the wordplay.
'rewriting' indicates anagramming the letters.
'with' is a charade indicator (letters next to each other).
'duet' put after 'lyric' is 'lyricduet'.
'lyricduet' with letters rearranged gives 'CREDULITY'.
'displaying' is the link.
(Other definitions for credulity that I've seen before include "Lack of worldly wisdom" , "naivety" , "Tendency to believe anything" , "Disposition to believe without sufficient evidence" , "Willingness to swallow anything" .)