Give your daughter the responsibility for getting her homework done, but set a time when she must stop working on it to complete such pre-bedtime activities as bathing, visiting with the family, or hearing a story before lights are off. Do not back away from this time even if your daughter has not finished her work and begs for more time. Also, have her give you her school books at this time every evening so she will not continue doing homework and get to bed late. She can get up early to complete unfinished work or finish it at school.
Having a set time for completing her homework is going to teach your daughter how to take initiative and to organize her time. Praise her when she handles it well. There is no reason for a parent to constantly press a good student to do his or her homework. The battles will only become worse as your child gets older.
If your daughter's defiance extends to threatening not to do any homework, point out that if her grades are lower because of her failure to do homework, there will be consequences and leave it at that. You may find it very helpful to read Ending The Homework Hassle by John Rosemond. It offers solid advice on homework issues as well as preventing and solving other school performance problems.