Upper level light on board (9)
I believe the answer is:
tableland
'upper level' is the definition.
(high level of ground)
'light on board' is the wordplay.
'light' becomes 'land' (I've seen this before).
'on' is a charade indicator (letters next to each other).
'board' becomes 'table' (synonyms).
'land' after 'table' is 'TABLELAND'.
(Other definitions for tableland that I've seen before include "Broad high plateau" , "Elevated area" .)