Parliamentarian turned up holding communication (5)
I believe the answer is:
'communication' is the definition.
(email is a kind of communication)
'parliamentarian turned up holding' is the wordplay.
'holding' says the answer is hidden in the clue.
'turned up' says the letters should be written in reverse.
'liame' can be found hidden inside 'parliamentarian'.
'liame' reversed gives 'EMAIL'.
(Other definitions for email that I've seen before include "Internet-borne communication" , "Message sent via computer" , "Messages between computer terminals" , "Send one online" , "Post" .)