One involved in gender-bending ruled (7)
I believe the answer is:
reigned
'ruled' is the definition.
(reigning is a kind of ruling)
'one involved in gender-bending' is the wordplay.
'one' becomes 'i' (Roman numeral).
'involved in' means one lot of letters goes inside another.
'bending' is an anagram indicator.
'gender' is an anagram of 'regned'.
'i' going inside 'regned' is 'REIGNED'.
(Other definitions for reigned that I've seen before include "Maintained high position" , "Ruled" , "Had sovereign power" , "Held sway" , "Was king" .)