Slogan putting student in stew (3,4)
I believe the answer is:
tag line
'slogan' is the definition.
(I've seen this before)
'student in stew' is the wordplay.
'student' becomes 'L' (as in L-plates for learner drivers).
'in' means one lot of letters goes inside another.
'stew' becomes 'tagine' (tagine is a type of North African stew).
'l' going inside 'tagine' is 'TAG LINE'.
'putting' is the link.
(Other definitions for tag line that I've seen before include "Something memorable one might say" , "End of joke" , "Catchphrase (mainly US)" , "Slogan" .)