Pioneer's heading (4)
I believe the answer is:
west
'pioneer's heading' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for west that I've seen before include "Small white dog" , "'Go ___ , young man'" , "Mae -, US actress; W" , "The cardinal compass point of 270 degrees" , "One Direction" .)