Fleece that is for beginner (6)
I believe the answer is:
rookie
'beginner' is the definition.
(I know that rookie is a type of beginner)
'fleece that is' is the wordplay.
'fleece' becomes 'rook' (I've seen this before).
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'rook'+'ie'='ROOKIE'
'for' is the link.
(Other definitions for rookie that I've seen before include "Novice" , "New recruit as to army" , "untrained soldier" , "Callow recruit" , "New (police) recruit (colloq.)" .)