Pest flying low round contemptible person (8)
I believe the answer is:
mosquito
'contemptible person' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'pest flying low round' is the wordplay.
'pest flying' becomes 'squit' (I can't justify this - if you can you should give a lot more credence to this answer).
'low' becomes 'moo' (both can mean to make the noise of a cow).
'round' is an insertion indicator.
'squit' inserted within 'moo' is 'MOSQUITO'.
Can you help me to learn more?
(Other definitions for mosquito that I've seen before include "Flying biting insect" , "WW2 fighter plane" , "Blood-sucking insect" , "Disease-bearing fly" , "possible disease carrier" .)