Female, heading off for Arabian sultanate (4)
I believe the answer is:
oman
'arabian sultanate' is the definition.
(I've seen this before)
'female heading off' is the wordplay.
'female' becomes 'woman' (woman is a kind of female).
'heading off' means to remove the first letter.
'woman' with its initial letter taken away is 'OMAN'.
'for' acts as a link.
(Other definitions for oman that I've seen before include "Sultanate on the south-east coast of the Arabian Peninsula" , "Arabian country, capital Muscat" , "Sultanate in southwest Asia" , "Arab country" , "Land" .)