Harris's insular associate (5)
I believe the answer is:
This might be a double definition.
'harris's' is the first definition.
Both the definition and answer are singular nouns.
Perhaps you can see a link between them that I don't see?
'insular associate' is the second definition.
The definition suggests a singular noun which matches the answer.
Can you help me to learn more?
(Other definitions for lewis that I've seen before include "Other half of Harris (Hebrides)" , "Hebridean isle" , "Police sergeant" , "- - Carroll, author" , "Cecil Day, C.S. or Jerry Lee" .)