Wine unknown in cooler shown upside-down (9)
I believe the answer is:
zinfandel
'wine' is the definition.
(zinfandel is a kind of wine)
'unknown in cooler shown upside-down' is the wordplay.
'unknown' becomes 'z' (algebra).
'cooler' becomes 'fan' (something which cools).
'shown' becomes 'led'.
'upside down' is a reversal indicator.
'led' backwards is 'del'.
'z'+'in'+'fan'+'del'='ZINFANDEL'
(Other definitions for zinfandel that I've seen before include "Californian grape variety" , "Dry wine" , "blush" , "Californian wine grape" , "Black grape grown in California" .)