Free - let out again (7)
I believe the answer is:
release
'free' is the definition.
(to release someone is to free them)
'let out again' is the wordplay.
I cannot quite understand how this works, but
'let' could be 'lease' (as in to lease or let a building) and 'lease' is found within the answer.
'again' could be 're' (prefix meaning 'again') and 're' is found in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for release that I've seen before include "Prisoner eagerly awaits this" , "Authorise publication" , "record" , "Issue" , "put out" .)