Final deposition indicates resolve (4)
I believe the answer is:
will
'resolve' is the definition.
(thesaurus)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for will that I've seen before include "A traditional question from the floor?" , "Final disposition" , "Intention; legal document" , "Intention; bequeath" , "Resolve - testament" .)