Robinson's change of course (6)
I believe the answer is:
crusoe
'robinson's' is the definition.
Both the definition and answer are singular nouns.
Perhaps you can see an association between them that I don't see?
'change of course' is the wordplay.
'change of' indicates an anagram (the letter order is changed).
'course' is an anagram of 'CRUSOE'.
Can you help me to learn more?
(Other definitions for crusoe that I've seen before include "Shipwreck victim" , "5 down [CASTAWAY]" , "Friday was his man" , "Robinson -, (Defoe's castaway)" , "One stranded" .)