That chap has reduced interest in bird book set in fabulous land (3,6)
I believe the answer is:
the hobbit
'reduced interest in bird book set in fabulous land' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'that chap' is the wordplay.
I cannot quite understand how this works, but
'chap' could be 'he' and 'he' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'has' is the link.
Can you help me to learn more?
(Other definitions for the hobbit that I've seen before include "fantasy" , "saga" , "Novel" .)