Chaste – kind of harpsichord (8)
I believe the answer is:
virginal
I believe this clue is a double definition.
'chaste' is the first definition.
(similar in meaning)
'kind of harpsichord' is the second definition.
(Other definitions for virginal that I've seen before include "Untouched - spinet" , "in immaculate condition" , "Untouched - smaller version of the harpsichord" , "Rectangular harpsichord" , "Pure - very early keyboard instrument" .)