Chap having German vote for Eurovision entry reduced (5)
I believe the answer is:
jason
'chap' is the definition.
(man's name)
'german vote for eurovision entry reduced' is the wordplay.
'german vote' becomes 'ja' ('yes' in German).
'for' says to put letters next to each other.
'eurovision entry' becomes 'song' (as in the Eurovision Song Contest).
'reduced' means to remove the last letter.
'song' with its final letter taken away is 'son'.
'ja'+'son'='JASON'
'having' acts as a link.
(Other definitions for jason that I've seen before include "Greek hero, leader of the Argonauts" , "Argonaut captain" , "He sailed in search of the Golden Fleece" , "He sailed the Argo to find the Golden Fleece" , "Leader of the Argonauts who sailed in quest of the Golden Fleece" .)