A second-rate remedy free (7)
I believe the answer is:
absolve
'free' is the definition.
(to absolve is to free or spare from blame)
'a second-rate remedy' is the wordplay.
'second' becomes 'b' (B can mean second eg B-side).
'rate remedy' becomes 'solve' (I can't explain this - if you can you should give a lot more credence to this answer).
'a'+'b'+'solve'='ABSOLVE'
Can you help me to learn more?
(Other definitions for absolve that I've seen before include "Clear of blame or guilt" , "Declare (someone) free of guilt" , "Excuse" , "free of error" , "Clear of blame or quilt" .)