Relaxed and let student off (5)
I believe the answer is:
eased
'relaxed' is the definition.
(I've seen this before)
'let student off' is the wordplay.
'let' becomes 'leased' (I've seen this before).
'student' becomes 'l' (as in L-plates for learner drivers).
'off' is a deletion indicator (some letters taken off).
'leased' with 'l' taken away is 'EASED'.
'and' is the link.
(Other definitions for eased that I've seen before include "became less tight" , "Alleviated" , "Became less painful" , "rested" , "Oiled" .)