Maybe Jack’s way to send greetings (4)
I believe the answer is:
card
'maybe jack's' is the definition.
(jack is a type of playing card)
'way to send greetings' is the wordplay.
'way' becomes 'rd' (short for road).
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'send greetings' becomes 'ca' (I can't explain this - if you can you should believe this answer much more).
'rd' put after 'ca' is 'CARD'.
Can you help me to learn more?
(Other definitions for card that I've seen before include "Birthday greeting" , "eccentric character" , "Posted greeting" , "Thick paper" , "Programme of events" .)