Phone back after seeing message on little folded card (7)
I believe the answer is:
notelet
'folded card' is the definition.
(a folded card or paper for writing a note on)
'phone back after seeing message' is the wordplay.
'phone' becomes 'tel' (short for telephone).
'back' says the letters should be written in reverse.
'after' is a charade indicator (letters next to each other).
'seeing message' becomes 'note' (note is a kind of message).
'tel' reversed gives 'let'.
'let' put after 'note' is 'NOTELET'.
'on little' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for notelet that I've seen before include "Small sheet for letter" , "Paper folded" , "Paper for informal letter" , "informal communication" , "Decorative letter" .)