The sonar is working here (5,3)
I believe the answer is:
north sea
'here' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'the sonar is working' is the wordplay.
'is working' is an anagram indicator.
'the'+'sonar'='thesonar'
'thesonar' is an anagram of 'NORTH SEA'.
Can you help me to learn more?
(Other definitions for north sea that I've seen before include "Area of natural gas" , "A great deal of water" , "Part of the Atlantic to the east of Great Britain" , "UK's source of oil, gas" , "Source of UK's oil/gas" .)