It could be indeed so unfair (3-5)
I believe the answer is:
one-sided
'unfair' is the definition.
(I've seen this before)
'it could be indeed so' is the wordplay.
'it could be' indicates anagramming the letters (I've seen this in other clues).
'indeed'+'so'='indeedso'
'indeedso' anagrammed gives 'ONE-SIDED'.
(Other definitions for one-sided that I've seen before include "Unilateral" , "So denied being partisan or unfair" , "Unfair or uneven" , "Indeed so (anag.)" , "Biased, favouring one part over another" .)