Ring a teacher at university, and name a drug (10)
I believe the answer is:
belladonna
'drug' is the definition.
(I've seen this before)
'ring a teacher at university and name a' is the wordplay.
'ring' becomes 'bell' (both can mean to call on the phone).
'teacher at university' becomes 'don'.
'and' means one lot of letters go next to another.
'name' becomes 'n' (common abbreviation e.g. on forms).
'bell'+'a'+'don'+'n'+'a'='BELLADONNA'
(Other definitions for belladonna that I've seen before include "plant" , "Deadly nightshade or atropine" , "drug supplier" , "brought a sparkle to the eye" , "Could it poison" .)