Nonet composed in some joint (5)
I believe the answer is:
tenon
'some joint' is the definition.
(I've seen this in other clues)
'nonet composed' is the wordplay.
'composed' indicates an anagram.
'nonet' anagrammed gives 'TENON'.
'in' is the link.
(Other definitions for tenon that I've seen before include "Tongue of wood, fits into mortise" , "Piece to fit into mortise" , "Mortise extension" , "Wood fitting into a mortise" , "One projecting" .)