Leader in Rome close to Spanish Pope (7)
I believe the answer is:
hadrian
'leader in rome' is the definition.
(Hadrian was a Roman emperor)
'close to spanish pope' is the wordplay.
'close to' indicates one should take the final letters (the close/ending of).
'pope' becomes 'Adrian' (Pope Adrian).
The last letter of 'spanish' is 'h'.
'h'+'adrian'='HADRIAN'
(Other definitions for hadrian that I've seen before include "Imperial wall-builder" , "Wall-building Roman emperor" , "His wall crosses northern Britain" , "Roman Emperor after Trajan" , "Roman emperor who built the British wall" .)