Listen out for mum (6)

I believe the answer is:

silent

'for mum' is the definition.
(to keep mum can informally mean to stay silent)

'listen out' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'listen' is an anagram of 'SILENT'.

(Other definitions for silent that I've seen before include "Listen, being speechless after 10 across" , "Making no sound" , "Wordless" , "Mute" , "Not speaking" .)

I've seen this clue in The Times, The Sunday Times and The Telegraph.

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