Crossword Genius

Robust binder (9)

Ross

I believe the answer is:

strapping

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'robust' is the definition.
(similar in meaning)

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for strapping that I've seen before include "Brawny" , "Big" , "Tying up" , "Robust" , "Burly" .)

I've seen this clue in The Telegraph.
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