Shin keeps itching in fleece (9)
I believe the answer is:
sheepskin
'fleece' is the definition.
(synonyms)
'shin keeps itching' is the wordplay.
'shin' becomes 'skin' (synonyms).
'keeps' is an insertion indicator.
'itching' becomes 'heeps' (I can't justify this - if you can you should give a lot more credence to this answer).
'skin' going around 'heeps' is 'SHEEPSKIN'.
'in' is the link.
Can you help me to learn more?
(Other definitions for sheepskin that I've seen before include "Body covering of an ovine mammal" , "Fleece garment" , "Woolly pelt" , "leather" , "coat" .)