Hang out with horrible characters, becoming like Boris, ironically (5,10)
I believe the answer is:
right honourable
'like boris ironically' is the definition.
(title for some MPs eg Boris Johnson)
'hang out with horrible characters' is the wordplay.
'with' means one lot of letters go next to another.
'characters' is an anagram indicator.
'hang'+'out'+'horrible'='hangouthorrible'
'hangouthorrible' is an anagram of 'RIGHT HONOURABLE'.
'becoming' acts as a link.
(Other definitions for right honourable that I've seen before include "What Gove might be called" , "PC title" , "address added to PC" .)