Drab sort of writer (4)
I believe the answer is:
bard
'writer' is the definition.
(I know that bard is a type of writer)
'drab sort' is the wordplay.
'sort' is an anagram indicator.
'drab' with letters rearranged gives 'BARD'.
'of' is the link.
(Other definitions for bard that I've seen before include "Traditional poet" , "Celtic poet" , "Gray, perhaps" , "Shakespeare" , "Eisteddfod winner" .)