Sent by tube (5)
I believe the answer is:
piped
'sent' is the definition.
The definition and answer can be both to do with communicating as well as being past participle verbs.
Perhaps they are linked in a way I don't understand?
'tube' is the wordplay.
I cannot really understand how this works, but
'tube' could be 'pipe' ('pipe' can be a synonym of 'tube') and 'pipe' is present in the answer.
A single letter 'd' remains which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
'by' is the link.
Can you help me to learn more?
(Other definitions for piped that I've seen before include "Transported by Tube" , "Taken from place to place, as water < music" .)