Englishman can brag... (4,4)

I believe the answer is:

john bull

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'englishman' is the definition.
(John Bull is an example)

'can brag' is the wordplay.
'can' becomes 'john' (slang for toilet).
'brag' becomes 'bull' (I can't justify this - if you can you should believe this answer much more).
'john'+'bull'='JOHN BULL'

Can you help me to learn more?

(Other definitions for john bull that I've seen before include "A typical Englishman of taurine type" , "Typical Englishman, sign Taurus" , "Archetypal Englishman" , "England personified" , "quintessential Englishman" .)

I've seen this clue in The Hindu.

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