Answer:

uncurl

Answer	Crossword Clue
UNCURL	Straighten, as hair
UNCURL	Straighten out
UNCURL	Relax, as one's toes

UNCURL	Straighten, as tresses
UNCURL	Straighten hair
UNCURL	Open, as a fern frond
UNCURL	Climb out of a comfy chair, perhaps
UNCURL	Straighten.
UNCURL	Straighten out.
UNCURL	Go straight?
UNCURL	Straighten, in a way