Initially blurting out such horrendous nonsense (4)

I believe the answer is:

bosh

'nonsense' is the definition.
(I know that bosh is a type of nonsense)

'initially blurting out such horrendous' is the wordplay.
'initially' suggests taking the first letters.
The first letters of 'blurting out such horrendous' is 'BOSH'.

(Other definitions for bosh that I've seen before include "Twaddle" , "Nonsense!" .)

I've seen this clue in The Times.

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