Crossword Genius

One discovers knowledge preserved by old priest (8)

Ross

I believe the answer is:

explorer

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

'one' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.

'discovers knowledge preserved by old priest' is the wordplay.
I cannot really understand how this works, but
'knowledge' could be 'lore' (lore is a kind of knowledge) and 'lore' is found in the answer.
'by' could be 'x' (multiplication sign) and 'x' is found in the answer.
'priest' could be 'pr' and 'pr' is located in the leftover letters.
A single letter 'e' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...

Can you help me to learn more?

(Other definitions for explorer that I've seen before include "Traveller seeking discoveries" , "Someone who visits unfamiliar areas" , "old satellite" , "Adventurer in unknown regions" , "Investigative traveller" .)

I've seen this clue in The Independent.
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