In red, write "Rent Free" (8)
I believe the answer is:
released
'free' is the definition.
(similar in meaning)
'in red write rent' is the wordplay.
'in' is an insertion indicator.
'write rent' becomes 'lease' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'red' enclosing 'lease' is 'RELEASED'.
Can you help me to learn more?
(Other definitions for released that I've seen before include "Let out - let out again" , "Liberated" , "Set free" , "free after imprisonment?" , "Sent from prison" .)