Gave birth to dull person (4)
I believe the answer is:
bore
I believe this is a double definition.
'gave birth to' is the first definition.
'dull person' is the second definition.
(I've seen this before)
(Other definitions for bore that I've seen before include "Carried - drill" , "Hollow barrel" , "Pierce - weary - tidal flood" , "Calibre of gun - nuisance" , "Weary with tediousness" .)