Have a duty, even if it might be tough? (5)

I believe the answer is:

ought

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'have a duty' is the definition.
(if you ought to do something it is your duty)

'even if it might be tough?' is the wordplay.
'tough' anagrams to 'OUGHT'.
Though, I am not clear how the anagram is indicated.

Can you help me to learn more?

(Other definitions for ought that I've seen before include "Be logically necessary" , "Strange thing" , "Be bound" , "Tough (anag)" , "Anything at all (archaic)" .)

I've seen this clue in The Globe and Mail and The Irish Independent.

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