Change course, finding equestrian gear (4)
I believe the answer is:
tack
I believe this is a double definition.
'change course' is the first definition.
(I've seen this in another clue)
'equestrian gear' is the second definition.
(I've seen this in another clue)
'finding' acts as a link.
(Other definitions for tack that I've seen before include "Small broad-headed nail" , "Nail - direction (eg of boat)" , "Poor food" , "Small nail; sail (boat) against the wind" , "Nail; tasteless material" .)