A boring president, awfully mundane (10)
I believe the answer is:
pedestrian
'mundane' is the definition.
(thesaurus)
'a boring president awfully' is the wordplay.
'boring' indicates putting letters inside (some letters must 'bore' a hole into other letters).
'awfully' is an anagram indicator.
'president' is an anagram of 'pedestrin'.
'a' put inside 'pedestrin' is 'PEDESTRIAN'.
(Other definitions for pedestrian that I've seen before include "nothing much to write home about" , "Dull; walker" , "not very fast" , "Unimaginative" , "Unexciting" .)