Unintroduced loan shark is more confident (5)

I believe the answer is:

surer

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'more confident' is the definition.
('sure' can be similar in meaning to 'confident')

I don't understand the remainder of the clue.

(Other definitions for surer that I've seen before include "faster" , "More certain and positive" , "more right?" .)

I've seen this clue in The Telegraph.

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