Ruler backing representative in Italian city (7)
I believe the answer is:
emperor
'ruler' is the definition.
(I've seen this before)
'backing representative in italian city' is the wordplay.
'backing' shows that the letters should be reversed in order.
'representative' becomes 'rep' (rep is a kind of representative).
'in' is an insertion indicator.
'italian city' becomes 'rome' (I've seen this before).
'rep' put into 'rome' is 'rorepme'.
'rorepme' backwards is 'EMPEROR'.
(Other definitions for emperor that I've seen before include "Beethoven piano concerto, Op. 73" , "Napoleon Bonaparte, for instance" , "Large richly coloured butterfly" , "eg Nero" , "chap such as Charlemagne" .)