Emperor owned Iran in a new layout (7)
I believe the answer is:
hadrian
'emperor' is the definition.
(Roman emperor)
'owned iran in a new layout' is the wordplay.
I cannot quite see how this works, but
'owned' could be 'had' ('have' can be a synonym of 'own') and 'had' is found within the answer.
an anagram of 'iran' is 'rian' which is located in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for hadrian that I've seen before include "Roman emperor who built the British wall" , "Roman emperor and wallbuilder" , "Roman Emperor after Trajan" , "Roman emperor who visited Britain" , "Wall-building Roman emperor" .)