Sensible mate, going round polar region, right in the lead (9)
I believe the answer is:
practical
'sensible' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for practical that I've seen before include "Experiment" , "Effective; virtual" , "Exam" , "Functional, pragmatic" , "Concerned with doing rather than with theory" .)