Bound to get a share of the treasure (4)

I believe the answer is:

sure

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

'bound to' is the definition.
(synonyms)

'a share of the treasure' is the wordplay.
'SURE' is hidden within the letters.
But, I am unsure how this is indicated.

'get' acts as a link.

Can you help me to learn more?

(Other definitions for sure that I've seen before include "Convinced" , "Positive" , "Completely certain" , "Feeling no doubt" , "Certain, confident" .)

I've seen this clue in the Evening Standard.

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