A president, oddly dull (10)
I believe the answer is:
pedestrian
'dull' is the definition.
('pedestrian' can be similar in meaning to 'dull')
'a president oddly' is the wordplay.
'oddly' is an anagram indicator.
'a'+'president'='apresident'
'apresident' is an anagram of 'PEDESTRIAN'.
(Other definitions for pedestrian that I've seen before include "Person walking" , "chap on zebra could be?" , "Unexciting" , "flat" , "A person travelling on foot" .)