Honourable and gentle, but one's less than grand? (7,5)
I believe the answer is:
upright piano
'one's less than grand?' is the definition.
(piano smaller than a grand piano)
'honourable and gentle' is the wordplay.
'honourable' becomes 'upright' (I've seen this before).
'and' says to put letters next to each other.
'gentle' becomes 'piano' (piano means soft or quiet in Italian).
'upright'+'piano'='UPRIGHT PIANO'
'but' acts as a link.
(Other definitions for upright piano that I've seen before include "Keyboard instrument" , "Musical instrument smaller than a grand" , "The old joanna" .)