President with a new flat (10)
I believe the answer is:
pedestrian
'flat' is the definition.
(I've seen this before)
'president with a new' is the wordplay.
'with' is a charade indicator (letters next to each other).
'new' indicates an anagram.
'president'+'a'='presidenta'
'presidenta' is an anagram of 'PEDESTRIAN'.
(Other definitions for pedestrian that I've seen before include "chap on zebra could be?" , "lacking inspiration" , "Run-of-the mill" , "nothing much to write home about" , "not very fast" .)