Terrible bog - all over the world (6)
I believe the answer is:
global
'world' is the definition.
(I know that world can be written as global)
'terrible bog all over' is the wordplay.
'terrible' indicates anagramming the letters.
'over' means one lot of letters go next to another (in a down clue, some letters go over others).
'bog' put after 'all' is 'allbog'.
'allbog' anagrammed gives 'GLOBAL'.
'the' acts as a link.
(Other definitions for global that I've seen before include "all over the place" , "Planetary" , "Going round the world" , "Universal" , "Affecting the whole world" .)