Love, marry, it's an obligation (4)

I believe the answer is:

owed

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'it's an obligation' is the definition.
I can't tell whether this defines the answer.

'love marry' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'marry' becomes 'we'd' (synonyms).
'o'+'wed'='OWED'

Can you help me to learn more?

(Other definitions for owed that I've seen before include "Outstanding" , "Was due to pay" , "(Sum) due for payment" , "Had a duty to pay" , "Was indebted" .)

I've seen this clue in the Sydney Morning Herald.

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