As before, it's no loss! (5)
I believe the answer is:
again
'as' is the definition.
Both the answer and definition are adverbs. Perhaps there's a link between them I don't understand?
'it's no loss' is the wordplay.
'it's' becomes 'a' (I can't explain this - if you can you should give a lot more credence to this answer).
'no loss' becomes 'gain' (I've seen this in other clues).
'a'+'gain'='AGAIN'
'before' is the link.
Can you help me to learn more?
(Other definitions for again that I've seen before include "10 10 [AGAIN" , "Here we go ___" , "Ocne more" , "Predictably perhaps" , "Furthermore" .)