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

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

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

This is all the clue.

(Other definitions for need that I've seen before include "Rely on" , "''A friend in .... is a friend indeed''" , "Want - require(ment)" , "Shortage" , "state of distress" .)

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

Obligation (4)