Distinctive style or manner (4)
I believe the answer is:
vein
This clue is a double definition.
'distinctive style' is the first definition.
(I've seen this before)
'manner' is the second definition.
(I've seen this in another clue)
(Other definitions for vein that I've seen before include "Blood-carrying vessel" , "Seam of mineral" , "Leaf rib; ore layer in rock" , "Distinctive style" , "Part of the blood circulation system" .)