Packed drover cowed in the confusion (11)
I believe the answer is:
overcrowded
'packed' is the definition.
The answer and definition can be both to do with motion as well as being past participle verbs.
Perhaps you can see a link between them that I can't see?
'drover cowed in the confusion' is the wordplay.
'drover cowed' can be anagrammed to 'OVERCROWDED'.
Though, I am not clear how this is indicated.
Can you help me to learn more?
(Another definition for overcrowded that I've seen is " Many jails are".)