Oo! Mug plays silly marriage system (10)

I believe the answer is:

polygamous

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'oo mug plays silly marriage system' is the definition.
I can't judge whether this defines the answer.

'oo mug plays silly' is the wordplay.
'silly' indicates anagramming the letters.
'oo'+'mug'+'plays'='oomugplays'
'oomugplays' is an anagram of 'POLYGAMOUS'.

Can you help me to learn more?

(Another definition for polygamous that I've seen is " Having more than one wife or husband".)

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

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