Regret leaving right energy out of TV detective (5)

I believe the answer is:

morse

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'tv detective' is the definition.
(Inspector Morse)

'regret leaving right energy out of' is the wordplay.
'regret leaving right' becomes 'mrs' (I can't justify this - if you can you should believe this answer much more).
'energy' becomes 'e' (physics symbol as in E=mcr).
'out' indicates putting letters inside.
'of' becomes 'o''.
'mrs'+'e'='mrse'
'mrse' going around 'o' is 'MORSE'.

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(Other definitions for morse that I've seen before include "Colin Dexter's fictional detective" , "TV Oxford cop" , "Code; TV detective" , "Samuel ---, telegraph inventor" , "used to transmit messages" .)

I've seen this clue in The Mirror.

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