Dull or commonplace (10)
I believe the answer is:
pedestrian
This clue is a double definition.
'dull' is the first definition.
(similar in meaning)
'commonplace' is the second definition.
(I've seen this before)
(Other definitions for pedestrian that I've seen before include "he goes for a walk" , "Walker; prosaic" , "Hiker" , "lame" , "flat" .)