Ruler exercises right during Rome uprising (7)
I believe the answer is:
emperor
'ruler' is the definition.
(emperor is a kind of ruler)
'exercises right during rome uprising' is the wordplay.
'exercises' becomes 'pe' (Physical Education class).
'right' becomes 'r' (common abbreviation).
'during' is an insertion indicator.
'uprising' shows that the letters should be reversed in order.
'rome' backwards is 'emor'.
'pe'+'r'='per'
'per' inserted into 'emor' is 'EMPEROR'.
(Other definitions for emperor that I've seen before include "Ancient Roman ruler" , "eg Nero" , "Powerful ruler" , "Kaiser" , "Ruler of large territory" .)