It used to be played for a year out of season (8)
I believe the answer is:
psaltery
'it used to be played' is the definition.
The definition suggests a singular noun which matches the answer.
'a year out of season' is the wordplay.
'a' becomes 'per' (eg 'one a day' means 'one per day').
'year' becomes 'y'.
'out of' is an insertion indicator (some letters on the outside of others).
'season' becomes 'salt' (salt can mean to season with salt).
'per'+'y'='pery'
'pery' placed around 'salt' is 'PSALTERY'.
'for' is the link.
Can you help me to learn more?
(Other definitions for psaltery that I've seen before include "Dulcimer-like instrument" , "Ancient zither-like instrument" , "Obsolete stringed instrument" , "Musical instrument" , "something demanding pluck" .)