Mason and Dixon initially angry (3)

I believe the answer is:

mad

'angry' is the definition.
(similar in meaning)

'mason and dixon initially' is the wordplay.
'initially' says to take the initial letters.
The first letters of 'mason and dixon' is 'MAD'.

(Other definitions for mad that I've seen before include "Berserk" , "Deranged" , "Roused to anger" , "Aberrant" , "Idiotic" .)

I've seen this clue in The Sun.

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