Dull, repetitious (6)
I believe the answer is:
boring
This clue is a double definition.
'dull' is the first definition.
(I know that dull can be written as boring)
'repetitious' is the second definition.
(thesaurus)
(Other definitions for boring that I've seen before include "Tedious and tiring" , "Drilling - it's monotonous" , "Tedious, of no interest" , "Mentally wearying" , "Dull and repetitive, a turn-off" .)