Switch edges on dresses? That's rational (5)
I believe the answer is:
sober
'rational' is the definition.
(I've seen this in another clue)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for sober that I've seen before include "Unintoxicated" , "Not intoxicated" , "Temperate" , "Dry - dull" , "Abstemious - grave" .)