Lie around in the morning after returning message (5)
I believe the answer is:
'message' is the definition.
(email is a type of message)
'lie around in the morning after returning' is the wordplay.
'around' is an insertion indicator.
'in the morning' becomes 'am' (AM on a clock).
'after returning' says the letters should be written backwards.
'lie' going around 'am' is 'liame'.
'liame' written backwards gives 'EMAIL'.
(Other definitions for email that I've seen before include "Messages between computer terminals" , "Digital message" , "Message sent via computer" , "Post" , "Send one online" .)