In the UK, one who doesn't get on when being informal (6)
I believe the answer is:
briton
'in the uk one who doesn't' is the definition.
Although both the answer and definition are adjectives, I can't see how one could define the other.
'on when being informal' is the wordplay.
'on' means one lot of letters go next to another.
'when' becomes 'on' (I've seen this in other clues).
'being informal' becomes 'brit' (I am not sure about this - if you are sure you should believe this answer much more).
'on' after 'brit' is 'BRITON'.
'get' acts as a link.
Can you help me to learn more?
(Other definitions for briton that I've seen before include "Citizen of our next-door neighbour" , "Citizen of England, Scotland or Wales" , "Native of United Kingdom" , "UK native" , "UK citizen" .)