He evaluates the animal digging up roses (8)
I believe the answer is:
assessor
'he evaluates' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'animal digging up roses' is the wordplay.
I cannot really understand how this works, but
'animal' could be 'ass' (term for a donkey) and 'ass' is located in the answer.
an anagram of 'roses' is 'essor' which is present in the answer.
No letters remain.
This explanation may well be incorrect...
'the' is the link.
Can you help me to learn more?
(Other definitions for assessor that I've seen before include "property valuer" , "Official to evaluate property" , "Person valuing property" , "Insurance valuer" , "One values property" .)