TV connector, zero switches, piece behind back of clock (7)

I believe the answer is:

linkman

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'behind back of clock' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.

'tv connector zero switches piece' is the wordplay.
'tv connector' becomes 'k' (I can't explain this - if you can you should believe this answer much more).
'zero' becomes 'nil' (synonyms).
'switches' shows that the letters should be reversed in order (I've seen 'switching' mean this (switching direction)).
'piece' becomes 'man' (man can mean a chess piece).
'k'+'nil'='knil'
'knil' back-to-front is 'link'.
'link'+'man'='LINKMAN'

Can you help me to learn more?

(Other definitions for linkman that I've seen before include "one who once lit the way" , "He carried a torch" , "TV presenter" .)

I've seen this clue in The Guardian.

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