Ancient god of all? (3)

I believe the answer is:

pan

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

'ancient god' is the definition.
'Pan' can be an answer for 'god' (Pan is a Greek god). I'm unsure of the 'ancient' bit.

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for pan that I've seen before include "all in many words, initially" , "piece in the kitchen" , "A vessel; chimp genus" , "Shallow vessel" , "God of fields and woods" .)

I've seen this clue in the Evening Standard.

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