Demanding wicked hair covering in ... (9)
I believe the answer is:
stressful
'demanding' is the definition.
'wicked hair covering in' is the wordplay.
I cannot really understand how this works, but
'hair' could be 'tress' (tress is a kind of hair) and 'tress' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for stressful that I've seen before include "under great pressure" , "Very hard on the nerves" , "tense" , "Worrying" , "Creating tension" .)