Octet relied on resetting polygraph (3,8)

I believe the answer is:

lie detector

I'm a little stuck... Click here to teach me more about this clue!

'polygraph' is the definition.
(I've seen this in another clue)

'octet relied on resetting' is the wordplay.
'octet relied' can be anagrammed to 'LIE DETECTOR'.
But, I'm unsure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for lie detector that I've seen before include "Police polygraph" , "It may check someone's veracity" , "Editor elect (anag.)" , "Truth-finding machine" , "that should tell stories?" .)

I've seen this clue in The Daily Express.

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