Admit everything and cry afterwards (5)
I believe the answer is:
allow
'admit' is the definition.
(allowing is a kind of admiting)
'everything and cry afterwards' is the wordplay.
'everything' becomes 'all' (all things).
'and' means one lot of letters go next to another.
'cry afterwards' becomes 'ow' (I can't justify this - if you can you should give a lot more credence to this answer).
'all'+'ow'='ALLOW'
Can you help me to learn more?
(Other definitions for allow that I've seen before include "Sanction" , "praise no more" , "Tolerate" , "Licence" , "Admit as acceptable" .)