In cricket side, Australian student? Rubbish! (5)
I believe the answer is:
offal
'rubbish' is the definition.
(I've seen this in another clue)
'in cricket side australian student?' is the wordplay.
'in cricket side' becomes 'off' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'australian' becomes 'A' (common abbreviation).
'student?' becomes 'l' (as in L-plates for learner drivers).
'off'+'a'+'l'='OFFAL'
Can you help me to learn more?
(Other definitions for offal that I've seen before include "Liver or tongue, for example" , "Internal organs and entrails as food" , "Inner organs used for food" , "Internal organs of an animal some find tasty" , "Rubbishy bits of animal flesh" .)