Chilling in cab flanked by horse (7)
I believe the answer is:
macabre
'chilling' is the definition.
(I've seen this before)
'cab flanked by horse' is the wordplay.
'flanked by' indicates putting letters inside (other letters go on other side).
'horse' becomes 'mare' (mare is a kind of horse).
'cab' put within 'mare' is 'MACABRE'.
'in' is the link.
(Other definitions for macabre that I've seen before include "Ghastly, gruesome" , "Morbidly repellent" , "Chilling" , "Gruesome, suggesting death" , "gruesome result" .)