Poor quality harness — it’s breaking (10)

I believe the answer is:

trashiness

'poor quality' is the definition.
(poor or trashy quality)

'harness it's breaking' is the wordplay.
'breaking' indicates anagramming the letters.
'harness'+'its'='harnessits'
'harnessits' is an anagram of 'TRASHINESS'.

(Another definition for trashiness that I've seen is " Low quality".)

I've seen this clue in The Times.

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