Millions pass finally through Varanasi, perhaps turning spiritual (6)

I believe the answer is:

mystic

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

'spiritual' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

(Other definitions for mystic that I've seen before include "One seeking God through contemplation" , "Seer" , "Allegorical; sacredly obscure" , "intensely spiritual" , "Of spiritual significance" .)

I've seen this clue in The Hindu.

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