Ancient instrument — store it in cleaner area (7)
I believe the answer is:
cithara
'ancient instrument store' is the definition.
The definition suggests a singular noun which matches the answer.
'it in cleaner area' is the wordplay.
'in' indicates putting letters inside.
'cleaner' becomes 'char' (char can mean a cleaner).
'area' becomes 'a' (maths abbreviation).
'it' going inside 'char' is 'cithar'.
'cithar'+'a'='CITHARA'
Can you help me to learn more?
(Another definition for cithara that I've seen is " old instrument".)