Reggie Miller, for his entire NBA career (5)
I believe the answer is:
pacer
'reggie miller for his entire nba career' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for pacer that I've seen before include "Racing horse with an unusual gait" , "One who sets the running speed; horse" , "Horse; one setting speed" , "Racehorse" , "setting the rate" .)