Gate with card entry deactivated (6)
I believe the answer is:
wicket
'gate' is the definition.
(wicket is a kind of gate)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for wicket that I've seen before include "playing area" , "Small gate, for a cricketer?" , "Small gate - dismissal at cricket" , "Three stumps and two bails" , "Stumps and bails construction - success for a bowler" .)