The Kingdom of Lear has been changed by a motorway (5)
I believe the answer is:
realm
'the kingdom' is the definition.
(kingdom is a type of country or realm)
'lear has been changed by a motorway' is the wordplay.
I cannot quite see how this works, but
an anagram of 'lear' is 'real' which is present in the answer.
'motorway' could be 'm' (as in motorway names - M1, M4 etc) and 'm' is found in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'of' acts as a link.
Can you help me to learn more?
(Other definitions for realm that I've seen before include "Kingdom; field of interest" , "monarch's responsibility" , "Area of interest/activity" , "Dominion" , "the UK, perhaps" .)