Philosopher and ambassador come together (5)
I believe the answer is:
hegel
'philosopher' is the definition.
(German philosopher Georg Wilhelm Friedrich Hegel)
'ambassador come together' is the wordplay.
'ambassador' becomes 'HE' (His or Her Excellency).
'come together' becomes 'gel' (gel can mean to go together well).
'he'+'gel'='HEGEL'
'and' acts as a link.
(Other definitions for hegel that I've seen before include "German 'dialectic' philosopher" , "Georg Wilhelm ---, Ger. philosopher" , "German philosopher, d. 1831" .)