Clay protects wheel covers (9)

I believe the answer is:

mudguards

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'wheel covers' is the definition.
The definition and answer can be both man-made objects as well as being plural nouns.
Maybe they are linked in a way I don't understand?

'clay protects' is the wordplay.
'clay' becomes 'mud' (synonyms).
'protects' becomes 'guards' (guarding is a kind of protecting).
'mud'+'guards'='MUDGUARDS'

Can you help me to learn more?

I've seen this clue in The Irish Times.

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