Undergraduate tore up (and ate part of) hat (6)
I believe the answer is:
boater
'hat' is the definition.
(I know that boater is a type of hat)
'undergraduate tore up and ate part of' is the wordplay.
I cannot quite understand how this works, but
'part' could be 'te' (te is a kind of part) and 'te' is found in the answer.
'of' could be 'o' and 'o' is located in the answer.
The remaining letters 'bar' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for boater that I've seen before include "Sailor's straw hat" , "one going in the junk?" , "Hard flat straw hat, or person on water" , "Hat style" , "Stiff hat made of straw" .)