Ruler in east, one out of Shanghai (7)
I believe the answer is:
empress
'ruler' is the definition.
(empress is a kind of ruler)
'east one out of shanghai' is the wordplay.
'east' becomes 'e' ('E' can be a synonym of 'east').
'one' becomes 'i' (Roman numeral).
'out of' indicates named letters should be taken away.
'shanghai' becomes 'impress' ('impress' can be a synonym of 'shanghai').
'impress' with 'i' taken away is 'mpress'.
'e'+'mpress'='EMPRESS'
'in' is the link.
(Other definitions for empress that I've seen before include "leading lady" , "Female ruler" , "She rules a vast realm" , "Delilah?" , "Powerful woman" .)