One of a trio of writers in the family omitting pairs of leading characters (5)
I believe the answer is:
emily
'one of a trio of writers' is the definition.
(one of the three Bronte sisters)
I can't explain the rest of the clue.
(Other definitions for emily that I've seen before include "A Bronte sister" , "Girl's name" , "One of the Bronte sisters" , "-- Dickinson, US poet" , "Woman" .)