As a statesman, Ernest ... (5)
I believe the answer is:
bevin
'a statesman ernest' is the definition.
The definition suggests a singular noun which matches the answer.
'as' is the wordplay.
I cannot quite see how this works, but
'as' could be 'in' (I've seen this in other clues) and 'in' is found within the answer.
The remaining letters 'bev' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for bevin that I've seen is " Ernie ---, post-war Foreign Secretary".)