Wind resistance is bore (4)
I believe the answer is:
drag
This clue is a double definition.
'wind resistance' is the first definition.
(I've seen this in another clue)
'is bore' is the second definition.
(I've seen this before)
(Other definitions for drag that I've seen before include "Hunt without foxes" , "A bore (colloq.); lug" , "Pull along the ground - transvestite'-'s get-up" , "woman's attire" , "Tow" .)