Honest player but not a grand one (7,5)
I believe the answer is:
upright piano
'not a grand one' is the definition.
I can't judge whether this definition defines the answer.
'honest player' is the wordplay.
'honest' becomes 'upright' (I've seen this in another clue).
'player' becomes 'piano' (piano player is a kind of player).
'upright'+'piano'='UPRIGHT PIANO'
'but' acts as a link.
Can you help me to learn more?
(Other definitions for upright piano that I've seen before include "Keyboard instrument" , "The old joanna" , "Musical instrument smaller than a grand" .)