Crossword Genius

King wearing worthless items — that might do for Murphy (4,3)

Ross

I believe the answer is:

ring rot

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'king wearing worthless items that might do for murphy' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.

'king wearing worthless items' is the wordplay.
'king' becomes 'R' (abbreviation for rex, king in Latin).
'wearing' becomes 'in' (in certain clothing).
'worthless items' becomes 'grot' (I can't justify this - if you can you should give a lot more credence to this answer).
'r'+'in'+'grot'='RING ROT'

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I've seen this clue in The Independent.
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