Journalist turning up on street after game is most ill-mannered (6)
I believe the answer is:
rudest
'most ill-mannered' is the definition.
('rude' can be a synonym of 'ill-mannered')
'journalist turning up on street after game' is the wordplay.
'journalist' becomes 'ed' (short for editor).
'turning up' says the letters should be written backwards.
'on street' becomes 'st' (I've seen this in other clues).
'after' means one lot of letters go next to another.
'game' becomes 'ru' (rugby union).
'ed' in reverse letter order is 'de'.
'de'+'st'='dest'
'dest' put after 'ru' is 'RUDEST'.
'is' is the link.
(Other definitions for rudest that I've seen before include "Most bad mannered!" , "Most vulgar" , "Least polite, most unmannerly" , "Most ill-mannered" , "Most impolite" .)