Obligation - Crossword Clue, Answer and Explanation

'obligation' is the definition.
(I know that obligation can be written as duty)

This is all the clue.

(Other definitions for duty that I've seen before include "Levy - tax on imports" , "Service - tax - office" , "Not subject to customs tax" , "A tax; compulsory task" , "assignment" .)

I've seen this clue in the USA Today, the Sydney Morning Herald, The Mirror, The Sun, The Guardian, The Star Tribune, The Telegraph, the Evening Standard, the Newsday, the Universal, The Washington Post, The Independent, The New York Times, the Penny Press, the King Feature Syndicate and the LA Times.

'obligation' is the definition.
(I've seen this in another clue)

This is all the clue.

(Other definitions for onus that I've seen before include "'Responsibility, task or burden (4)'" , "Encumbrance" , "'Burden, load (4)'" , "Responsibilty" , "Liability" .)

I've seen this clue in the USA Today, the Sydney Morning Herald, The Mirror, The Sun, The Guardian, The Star Tribune, The Telegraph, the Evening Standard, the Newsday, the Universal, The Washington Post, The Independent, The New York Times, the Penny Press, the King Feature Syndicate and the LA Times.

'obligation' is the definition.
(I know that debt is a type of obligation)

This is all the clue.

(Other definitions for debt that I've seen before include "Money owed or due" , "Something owed" , "Arrears, liability" , "What's due" , "outstanding" .)

I've seen this clue in the USA Today, the Sydney Morning Herald, The Mirror, The Sun, The Guardian, The Star Tribune, The Telegraph, the Evening Standard, the Newsday, the Universal, The Washington Post, The Independent, The New York Times, the Penny Press, the King Feature Syndicate and the LA Times.

Obligation (4)