Become red in the face or hand (5)
I believe the answer is:
'become red' is the definition.
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for flush that I've seen before include "Poker hand of same suit" , "winning hand at poker" , "Look ashamed < , maybe even promising hand" , "Pull the chain - rush of emotion - good poker hand - having plenty of money" , "with a load of cash" .)