Student having talk about injury (6)
I believe the answer is:
lesion
'injury' is the definition.
(I know that lesion is a type of injury)
'student having talk about' is the wordplay.
'student' becomes 'L' (as in L-plates for learner drivers).
'having' is a charade indicator (letters next to each other).
'talk' becomes 'noise' (I have seen 'Public talk' mean 'noise' so perhaps 'talk' could also mean 'noise').
'about' shows that the letters should be reversed in order.
'noise' reversed gives 'esion'.
'l'+'esion'='LESION'
(Other definitions for lesion that I've seen before include "A cut or wound in insole" , "Flesh wound" , "Damaged area of tissue" , "Harmful change in bodily tissue as from injury" , "Damage to tissue from injury or disease" .)