Student into drink slowly makes blunder (4)
I believe the answer is:
slip
'blunder' is the definition.
(I know that slip is a type of blunder)
'student into drink slowly' is the wordplay.
'student' becomes 'l' (as in L-plates for learner drivers).
'into' indicates putting letters inside.
'drink slowly' becomes 'sip' (I've seen this before).
'l' inserted inside 'sip' is 'SLIP'.
'makes' acts as a link.
(Other definitions for slip that I've seen before include "Gaffe" , "Glide; petticoat" , "Mistake -- small piece of paper" , "Slight error" , "Minor error, stumble" .)