Greeting in post from wit (4)
I believe the answer is:
card
This might be a double definition.
'greeting in post' is the first definition.
'card' can be an answer for 'greeting' (card is a kind of greeting). I'm not sure about the 'in post' bit.
'wit' is the second definition.
(synonyms)
'from' acts as a link.
Can you help me to learn more?
(Other definitions for card that I've seen before include "Posted greeting" , "appears in a suit" , "club, for example" , "Comb (wool)" , "Jack, for one" .)