Strange omen, warning to go over first (7)
I believe the answer is:
foreign
'strange' is the definition.
('foreign' can be similar in meaning to 'strange')
'omen warning to go over first' is the wordplay.
I cannot quite understand how this works, but
'warning' could be 'fore' (I've seen this in other clues) and 'fore' is found in the answer.
'first' could be 'i' (I in Roman numerals eg Elizabeth I) and 'i' is present in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for foreign that I've seen before include "not appropriate" , "Overseas" , "not typical" , "Not domestic" , "Concerning other nations" .)