Make a mess of protecting student spot (6)
I believe the answer is:
blotch
'spot' is the definition.
(I've seen this before)
'make a mess of protecting student' is the wordplay.
'make a mess of' becomes 'botch' (I've seen this before).
'protecting' means one lot of letters goes inside another.
'student' becomes 'l' (as in L-plates for learner drivers).
'botch' placed around 'l' is 'BLOTCH'.
(Other definitions for blotch that I've seen before include "Irregular patch or mark" , "Spot of irregular discoloration" , "Irregular coloured mark" , "Unsightly patch" , "Large stain" .)