Straighten out (7)
(Another definition for uncurl that I've seen is " Straighten from rolled up position".)
(Other definitions for untwine that I've seen before include "Become unwound - wine nut (anag)" , "Unwind; untwist" , "Take the string off" , "Disentangle" , "Ravel to be dealt with" .)
(Other definitions for untwist that I've seen before include "free of entanglements" , "Dishevel" , "Sort out - release (cap on a plastic bottle?)" , "Perform opening" , "Straighten out" .)