Let one's hair down and removed all the curls from (6)
I believe the answer is:
unbent
'hair down and removed all the curls from' is the definition.
I can't tell whether this defines the answer.
'let one's' is the wordplay.
I cannot really understand how this works, but
'one' could be 'un' (northern English dialect form of 'one') and 'un' is found within the answer.
The remaining letters 'bent' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for unbent that I've seen before include "Remaining straight" , "Relaxed, straightened up" .)