Thus, again, it's fair (2-2)
I believe the answer is:
so-so
'fair' is the definition.
(I've seen this before)
'thus again' is the wordplay.
I cannot really understand how this works, but
'thus' could be 'so' (synonyms) and 'so' is located in the answer.
The remaining letters 'so' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
'it's' acts as a link.
Can you help me to learn more?
(Other definitions for so-so that I've seen before include "OK, but nothing special" , "Fair to middling" , "just about adequate" , "Of average quality" , "Only moderately good in repetitive way" .)