Pardon sailor to clear the matter up (7)
I believe the answer is:
absolve
'pardon' is the definition.
(I've seen this in another clue)
'sailor to clear the matter up' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'to clear the matter up' becomes 'solve' (I can't explain this - if you can you should give a lot more credence to this answer).
'ab'+'solve'='ABSOLVE'
Can you help me to learn more?
(Other definitions for absolve that I've seen before include "Fully pardon" , "free of error" , "Discharge" , "Acquit - free of blame" , "Excuse" .)