Informally, handle place crooks are awfully mean (8)
I believe the answer is:
nickname
'informally handle' is the definition.
'nickname' can be an answer for 'handle' (a handle is a name). I'm unsure of the 'informally' bit.
'place crooks are awfully mean' is the wordplay.
'place crooks' becomes 'nick' (I can't explain this - if you can you should give a lot more credence to this answer).
'are awfully' is an anagram indicator.
'mean' is an anagram of 'name'.
'nick'+'name'='NICKNAME'
Can you help me to learn more?
(Other definitions for nickname that I've seen before include "Familiar moniker" , "Add soubriquet to" , "term for someone" , "Familiar term of address" , "Jason say" .)