Release document one has to vacillate about (6)
I believe the answer is:
waiver
'release document' is the definition.
(type of legal document)
'one has to vacillate about' is the wordplay.
I cannot really see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
'vacillate' could be 'waver' (synonyms) and 'waver' is found in the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
(Other definitions for waiver that I've seen before include "Letting go right" , "Act of forgoing a right or claim" , "Formal for going of legal right or claim" , "surrender" , "withdrawal of claim" .)