Going down without head scarf is unseemly (8)
I believe the answer is:
indecent
'is unseemly' is the definition.
(synonyms)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for indecent that I've seen before include "Immodest, gross" , "not appropriate" , "Smutty" , "Gross, obscene" , "Lewd" .)