Rough seas face boat heading from Yalta (7)
I believe the answer is:
sketchy
'rough' is the definition.
(both can mean vague)
'seas face boat heading from yalta' is the wordplay.
'face' suggests taking the first letters.
'boat' becomes 'ketch' (ketch is a type of sailing boat).
'heading from yalta' becomes 'y' (I am not sure about this - if you are sure you should believe this answer much more).
The initial letter of 'seas' is 's'.
's'+'ketch'+'y'='SKETCHY'
Can you help me to learn more?
(Other definitions for sketchy that I've seen before include "Deep cave; evidence of road wear" , "first draft" , "Imprecise" , "Superficial" , "Incomplete; rough" .)