Card player before noon quiet — not up for port (11)
I believe the answer is:
southampton
'port' is the definition.
(I've seen this before)
'card player before noon quiet not up' is the wordplay.
'card player' becomes 'south' (bridge players are known by compass position).
'before noon' becomes 'AM' (as in AM on a clock).
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'up' is a reversal indicator (in down clue: letters go upwards).
'not' backwards is 'ton'.
'south'+'am'+'p'+'ton'='SOUTHAMPTON'
'for' acts as a link.
(Other definitions for southampton that I've seen before include "Mayflower starting port" , "Premiership football club" , "Port in Hampshire" , "Hampshire city" .)