Rodents solved crime after party (7)
I believe the answer is:
dormice
'rodents' is the definition.
(dormouse is a kind of rodent)
'solved crime after party' is the wordplay.
'solved' indicates an anagram (the anagram must be solved).
'after' says to put letters next to each other.
'party' becomes 'do' (do is a kind of party).
'crime' with letters rearranged gives 'rmice'.
'rmice' put after 'do' is 'DORMICE'.
(Other definitions for dormice that I've seen before include "For these heavy sleepers" , "Little hibernating rodents" , "Bushy-tailed rodents" , "Mammals" , "little things?" .)