Charlie’s parking by Barbican perhaps after pulling over (5)

I believe the answer is:
twerp
'over' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for twerp that I've seen before include "Pillock" , "In slang, a stupid or objectionable person" , "Twit" , "Silly-billy" , "Fool" .)
