Altering manner, lutist produces musical piece (12)
I believe the answer is:
instrumental
'musical piece' is the definition.
'altering manner lutist' is the wordplay.
'altering' indicates an anagram.
'manner'+'lutist'='mannerlutist'
'mannerlutist' is an anagram of 'INSTRUMENTAL'.
'produces' is the link.
(Other definitions for instrumental that I've seen before include "Having some responsibility - not vocal" , "doing without singers" , "Helpful; composition" , "Important" , "Piece of music without voices" .)