Music maker's last letter takes it to her (6)
I believe the answer is:
zither
'music maker's' is the definition.
(zither is a kind of musical instrument)
'last letter takes it to her' is the wordplay.
'last letter' becomes 'Z' (last letter of the alphabet).
'takes' says to put letters next to each other.
'to' is a charade indicator (letters next to each other).
'z'+'it'+'her'='ZITHER'
(Other definitions for zither that I've seen before include "Instrument played on the knee" , "Stringed instrument placed on the knee" , "Metal-stringed soundbox" , "Plucked musical instrument" , "Harp-like instrument" .)