Upset at a Roman, I found a girlfriend (9)
I believe the answer is:
inamorata
'a girlfriend' is the definition.
(an inamorata is a lover)
'upset at a roman i' is the wordplay.
'upset' is a reversal indicator.
'at'+'a'+'roman'+'i'='ataromani'
'ataromani' back-to-front is 'INAMORATA'.
'found' acts as a link.
(Other definitions for inamorata that I've seen before include "A woman loved" , "6 across [BOSOM] friend" , "Woman in love" , "Beloved of one another" , "Sweetheart" .)