After extremes of pace, pole positions altered in race (6)
I believe the answer is:
Here is my best explanation:
'race' is the definition.
'after extremes of pace pole positions altered' is the wordplay.
'after' says to put letters next to each other.
'extremes of' suggests removing the centre.
'positions altered' is an anagram indicator (the positions of the letters are altered).
'pace' with its centre removed is 'pe'.
'pole' with letters rearranged gives 'ople'.
'pe' next to 'ople' is 'PEOPLE'.
'in' is the link.
(Other definitions for people that I've seen before include "Men, women and children", "Race - mankind", "See 6", "Mortals", "Humans in general", "Human beings in general", "Humankind", "Persons in general", "Community" and "Nation".)