Chesspiece that is for beginner (6)
I believe the answer is:
rookie
'beginner' is the definition.
(rookie is a kind of beginner)
'chesspiece that is' is the wordplay.
'chesspiece' becomes 'rook' (I've seen this before).
'that is' becomes 'ie' ('i.e.' can be a synonym of 'that is').
'rook'+'ie'='ROOKIE'
'for' acts as a link.
(Other definitions for rookie that I've seen before include "Beginner as in the army" , "Callow recruit" , "Raw recruit" , "new team member" , "Army or police recruit" .)