Unattractive student tucking into French bread (5)
I believe the answer is:
plain
'unattractive' is the definition.
(similar in meaning)
'student tucking into french bread' is the wordplay.
'student' becomes 'l' (as in L-plates for learner drivers).
'tucking into' means one lot of letters goes inside another.
'french bread' becomes 'pain' (I've seen this before).
'l' put inside 'pain' is 'PLAIN'.
(Other definitions for plain that I've seen before include "Not elaborate; clear" , "Uncomplicated" , "Undecorated; clear" , "no oil painting features" , "lament" .)