Virtually a letter by word of mouth (7)

I believe the answer is:

morally

'virtually' is the definition.
(thesaurus)

'a letter by word of mouth' is the wordplay.
'a letter' becomes 'm'.
'by word of mouth' becomes 'orally' (I've seen this before).
'm'+'orally'='MORALLY'

(Another definition for morally that I've seen is " To all intents and purposes - in terms of right and wrong".)

I've seen this clue in the Evening Standard.

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