Dummy run in a mo, using bombing (9)
I believe the answer is:
ignoramus
'dummy' is the definition.
(thesaurus)
'run in a mo using bombing' is the wordplay.
I cannot really see how this works, but
'run' could be 'ram' ('ram' can be a synonym of 'run') and 'ram' is found in the answer.
This explanation may well be incorrect...
(Other definitions for ignoramus that I've seen before include "Ron is a mug (anag.)" , "Simpleton" , "Ignorant person" , "Dimwit" , "One is not intelligent" .)