Crossword Genius

Persist as Welsh symbol (6)

Ross

I believe the answer is:

dragon

'welsh symbol' is the definition.

I cannot understand how the rest of the clue works.

(Other definitions for dragon that I've seen before include "battleaxe" , "Flying monster of Welsh legend" , "Fire breathing mythological creature" , "Continue interminably" , "Fail tediously to conclude" .)

I've seen this clue in The Guardian.
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