Composer from Hanover discovered (5)
I believe the answer is:
verdi
'composer' is the definition.
(I've seen this before)
'from hanover discovered' is the wordplay.
'from' indicates a hidden word.
'VERDI' can be found hidden inside 'hanover discovered'.
(Other definitions for verdi that I've seen before include "Giuseppe -----, 1813-1901, prolific opera composer" , "Diver became a strange composer" , "Il trovatore composer" , "Emblem of the Knights Hospitallers" , "Giuseppe _____, composer of "La Traviata"" .)