Perhaps one in eight might, after change of leader (5)
I believe the answer is:
rower
'perhaps one in eight' is the definition.
(an eight is a rowing crew of eight rowers)
I don't understand how the remainder of the clue works.
(Other definitions for rower that I've seen before include "Waterman" , "Sportsperson" , "Oarswoman or oarsman" , "Stroke with blade" , "crew member, perhaps" .)