Withstand sister's manoeuvre (6)
I believe the answer is:
resist
'withstand' is the definition.
(I know that resist is a is a more specific form of the action of withstand)
'sister's manoeuvre' is the wordplay.
'manoeuvre' indicates anagramming the letters.
'sister' is an anagram of 'RESIST'.
(Other definitions for resist that I've seen before include "Don't give in" , "Use force to prevent something from happening to sister" , "Defy for sister" , "Withstand, oppose" , "Fight back" .)