Tedious one (4)
I believe the answer is:
bore
'tedious one' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for bore that I've seen before include "Tedious chap" , "Tedious person; steep wave" , "Dull person; tidal wave" , "Dull person; use a drill" , "Tedious person - wave - make a hole" .)