Great evening meal down by a piano? (5)
I believe the answer is:
super
'great' is the definition.
(both can mean excellent)
'evening meal down by a piano?' is the wordplay.
'evening meal' becomes 'supper' (I've seen this before).
'down by a' indicates named letters should be taken away (to be down to something is to be missing it).
'piano?' becomes 'p' (musical abbreviation).
'supper' with 'p' taken away is 'SUPER'.
(Other definitions for super that I've seen before include "First-rate, top-notch" , "of high quality" , "Marvellous, terrific" , "Jolly good" , "Brilliant" .)