Attack on TV? (5)

I believe the answer is:

onset

'attack' is the definition.
(archaic term for a military attack)

'on tv' is the wordplay.
'tv' becomes 'set' (television set).
'on'+'set'='ONSET'

(Other definitions for onset that I've seen before include "Storming" , "First signs" , "Beginning; military attack" , "Appearance of" , "Start - notes (anag)" .)

I've seen this clue in The Irish News, The Telegraph and the Evening Standard.

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