Trouble in Scotland for one idiot heading north (5)
I believe the answer is:
midge
'trouble in scotland' is the definition.
(midges are common in Scotland)
'for one idiot heading north' is the wordplay.
'for one' becomes 'eg' (I've seen this in other clues).
'idiot' becomes 'dim' (both can mean stupid).
'heading north' says the letters should be written in reverse.
'eg'+'dim'='egdim'
'egdim' in reverse letter order is 'MIDGE'.
(Other definitions for midge that I've seen before include "Small biting fly" , "Small flying insect" , "Small swarming biting insect" , "Small, gnat-like fly" , "Tiny swarming insect" .)