Mountain climber suffering in tailspin (8)
I believe the answer is:
alpinist
'mountain climber' is the definition.
(alpinist is a kind of mountain climber)
'suffering in tailspin' is the wordplay.
'suffering in' indicates an anagram (letters suffer disruption).
'tailspin' with letters rearranged gives 'ALPINIST'.
(Other definitions for alpinist that I've seen before include "one climbs" , "Maker of sharp climb" , "mountaineer" , "Climber of big mountains" .)