Telegraphs (6)
I believe the answer is:
cables
'telegraphs' is the definition.
('cable' can be a synonym of 'telegraph')
This is the entire clue.
(Other definitions for cables that I've seen before include "Thick wires" , "Thick wire ropes or old telegrams" , "Conductors for transmitting electricity" , "Hawsers" , "Electrical conductors connecting telephones or television, say" .)