Quick to show what you feel (7)

I believe the answer is:

express

I'm a little stuck... Click here to teach me more about this clue!

'quick' is the definition.
(I've seen this before)

I don't understand the remainder of the clue.

(Other definitions for express that I've seen before include "Fast train; specific" , "set forth" , "Utter - direct" , "air" , "Speak - fast" .)

I've seen this clue in the Evening Standard.

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