Great puzzle as usual on a Sunday.
Second family member entering college once, maybe (8) = POSSIBLY
second = S, family member = SIB, college once = POLY
First points for big win as all the leaders have quit (7) = ORIGINS
leaders have quit = delete first letters.
Those serving, with score in mind (8) = MENTALLY
Those serving = MEN, score = TALLY
SIB = family member