Leave out some indomitable characters (4)
I believe the answer is:
omit
'leave out' is the definition.
(I know that leave out can be written as omit)
'some indomitable characters' is the wordplay.
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'OMIT' is hidden within 'indomitable characters'.
(Other definitions for omit that I've seen before include "Neglect to include" , "Miss out" , "Leave out or exclude" , "Fail (to do something)" , "Disregard" .)