Blockhead student in a spot (4)
I believe the answer is:
dolt
'blockhead' is the definition.
(thesaurus)
'student in a spot' is the wordplay.
'student' becomes 'l' (as in L-plates for learner drivers).
'in' indicates putting letters inside.
'a spot' becomes 'dot' (I've seen this before**).
'l' placed into 'dot' is 'DOLT'.
(Other definitions for dolt that I've seen before include "Dunce" , "Dull or stupid fellow" , "Fool" , "Dullard" , "Slow-witted person" .)