Passes on (a message) (6)
I believe the answer is:
relays
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">passes on a message</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for relays that I've seen before include "Receives and passes on" , "Races featuring running teams and baton passing" , "Races where a baton is passed from one to another" , "Races with team members who pass a baton" , "Transmits" .)