Clare arranged to include Violet on keyboard (7)
I believe the answer is:
clavier
'keyboard' is the definition.
(clavier is a kind of keyboard)
'clare arranged to include violet' is the wordplay.
'arranged' indicates an anagram.
'to include' is an insertion indicator.
'violet' becomes 'vi'.
'clare' is an anagram of 'claer'.
'claer' placed around 'vi' is 'CLAVIER'.
'on' is the link.
(Other definitions for clavier that I've seen before include "Stringed instrument with a keyboard" , "Bach played it" , "Instrumental keyboard" .)