Crossword Genius

How to make new doors fail test of reliability (5,4,4)

Ross

I believe the answer is:

break ones word

'fail test of reliability' is the definition.
(breaking one's word means being unreliable)

'how to make new doors' is the wordplay.
'how' becomes 'break' (I can't explain this - if you can you should believe this answer much more).
'to make' indicates an anagram.
'new'+'doors'='newdoors'
'newdoors' is an anagram of 'onesword'.
'break'+'onesword'='BREAK ONES WORD'

I've seen this clue in The Guardian.
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