A meal goes down fine, gathered round the piano (6)
I believe the answer is:
supper
'a meal' is the definition.
(supper is a kind of meal)
'goes down fine gathered round the piano' is the wordplay.
'goes down fine' becomes 'super' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'gathered round' is an insertion indicator.
'the piano' becomes 'p'.
'super' going around 'p' is 'SUPPER'.
Can you help me to learn more?
(Other definitions for supper that I've seen before include "Light, late, meal" , "Last meal of the day" , "singing for this?" , "Evening 2 Down" , "consumer" .)