Dreary, uninteresting (4)
I believe the answer is:
dull
This clue is a double definition.
'dreary' is the first definition.
(similar in meaning)
'uninteresting' is the second definition.
(similar in meaning)
(Other definitions for dull that I've seen before include "Drab" , "Uninspiring" , "Obtuse - tedious - cloudy" , "Not shiny; uninteresting" , "Dreary" .)