Evaluator's a blockhead, always hesitating (7)
I believe the answer is:
assayer
'evaluator's' is the definition.
Both the answer and definition are singular nouns.
Perhaps they are linked in a way I don't understand?
'a blockhead always hesitating' is the wordplay.
'a blockhead' becomes 'ass' (I've seen this in another clue).
'always' becomes 'ay' (archaic term for 'always').
'hesitating' becomes 'er'.
'ass'+'ay'+'er'='ASSAYER'
Can you help me to learn more?
(Other definitions for assayer that I've seen before include "Analyser of minerals" , "Metal/ore tester" , "Tester of fine metal" , "One tests minerals" , "I'll carry out a test" .)