Player of instruments, one group of notes first (14)
I believe the answer is:
harpsichordist
'player' is the definition.
(harpsichordist is a kind of player)
'instruments one group of notes first' is the wordplay.
'instruments' becomes 'harps' (harp is a kind of instrument**).
'one' becomes 'i' (Roman numeral).
'group of notes' becomes 'chord' (I've seen this before).
'first' becomes 'ist'.
'harps'+'i'+'chord'+'ist'='HARPSICHORDIST'
'of' is the link.
(Other definitions for harpsichordist that I've seen before include "Keyboard player" , "Scarlatti, say" , "Continuo player possibly" .)