Eager moving round cities' haunts (12)
I believe the answer is:
enthusiastic
'eager' is the definition.
(similar in meaning)
'moving round cities' haunts' is the wordplay.
'moving round' indicates an anagram.
'cities'+'haunts'='citieshaunts'
'citieshaunts' with letters rearranged gives 'ENTHUSIASTIC'.
(Other definitions for enthusiastic that I've seen before include "Full of fervour" , "Showing great interest" , "Highly keen" , "Ardent, zealous" , "Showing keen interest" .)