An outlaw let out of the bag (4)
I believe the answer is:
tell
'an outlaw' is the definition.
(I know that disallow is a is a more specific form of the action of outlaw)
'let out of the bag' is the wordplay.
'out of' is an anagram indicator.
'the bag' becomes 'l' (I can't explain this - if you can you should give a lot more credence to this answer).
'let' anagrammed gives 'tel'.
'tel'+'l'='TELL'
Can you help me to learn more?
(Other definitions for tell that I've seen before include "Notify" , "Issue instructions" , "Count - give an account" , "Peach" , "work in a bank" .)