More addled student being dropped (5)
I believe the answer is:
added
'more' is the definition.
(similar in meaning)
'addled student being dropped' is the wordplay.
'student' becomes 'L' (as in L-plates for learner drivers).
'being dropped' suggests deleting specific letters (some letters are excluded or dropped).
'addled' with 'l' removed is 'ADDED'.
(Other definitions for added that I've seen before include "Totted" , "Said" , "Appended; totalled" , "Summed up" , "Counted up" .)