Sovereign with nothing on (4)
I believe the answer is:
free
This clue is a double definition.
'sovereign' is the first definition.
('free' can be similar in meaning to 'sovereign')
'with nothing on' is the second definition.
(Other definitions for free that I've seen before include "Not confined" , "Release; without cost" , "Liberated" , "Not working" , "Type of tenure" .)