Old instrument of temptation (7)

I believe the answer is:

serpent

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

'old instrument' is the definition.
'serpent' can be an answer for 'instrument' (serpent is a kind of instrument). I'm unsure of the 'old' bit.

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

Can you help me to learn more?

(Other definitions for serpent that I've seen before include "the first lady found beguiling" , "Snake - old wind instrument" , "exhibit at zoo" , "Limbless reptile" , "Early wind instrument" .)

I've seen this clue in The Irish News.

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