Crossword Genius

Coin a phrase to describe an octet? (5,2,5)

Ross

I believe the answer is:

piece of eight

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

'coin' is the definition.
(piece of eight is a kind of coin)

'a phrase to describe an octet?' is the wordplay.
I cannot quite see how this works, but
'an' could be 'i' (Roman numeral for one) and 'i' is found in the answer.
'octet?' could be 'eight' (synonyms) and 'eight' is found within the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?

I've seen this clue in The Telegraph.
Want a hint initially instead of a full solution? Install my app