Former Lib Dem leader's message ... (5)

I believe the answer is:

cable

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'message' is the definition.
(cable is a kind of message)

I don't understand how the rest of the clue works.

(Other definitions for cable that I've seen before include "A message transmitted" , "Telegram; thick rope" , "Strong rope made of twisted strands of hemp, nylon or steel wire" , "Strong line" , "This may pull car up" .)

I've seen this clue in The Telegraph.

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