Mountain flower on the right in bog (8)
I believe the answer is:
lavatory
'bog' is the definition.
(thesaurus)
'mountain flower on the right' is the wordplay.
'mountain flower' becomes 'lava' (lava might flow down a mountain).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'the right' becomes 'tory' (Tory can mean Conservative or right-wing).
'lava'+'tory'='LAVATORY'
'in' is the link.
(Other definitions for lavatory that I've seen before include "Ladies or Gentlemen" , "somewhere to go?" , "John for American" , "one's flushed" , "Something to go on" .)