Student in widespread rummage (5)
I believe the answer is:
rifle
'rummage' is the definition.
(I've seen this before)
'student in widespread' is the wordplay.
'student' becomes 'l' (as in L-plates for learner drivers).
'in' is an insertion indicator.
'widespread' becomes 'rife' (I've seen this before).
'l' going into 'rife' is 'RIFLE'.
(Other definitions for rifle that I've seen before include "Gun - ransack" , "Gun with long_barrel" , "Security provider with stock" , "Root" , "Firearm - plunder" .)