Student has ace material (4)
I believe the answer is:
lace
'material' is the definition.
(lace is a kind of material)
'student has ace' is the wordplay.
'student' becomes 'l' (as in L-plates for learner drivers).
'has' is a charade indicator (letters next to each other).
'l'+'ace'='LACE'
(Other definitions for lace that I've seen before include "Fabric made in openwork design" , "Delicate material" , "Fine open fabric" , "Fine needlework" , "Spike - ornamental fabric" .)