Courageous rogue has left to overcome resistance (7)

I believe the answer is:

valiant

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'courageous' is the definition.
('valiant' can be similar in meaning to 'courageous')

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for valiant that I've seen before include "Doughty" , "Courageous, determined" , "Brave - resolute" , "Brave in battle" , "Heroic" .)

I've seen this clue in The Telegraph.

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