So, though superficial, we are objective (4)
I believe the answer is:
thus
'so' is the definition.
(I know that so can be written as thus)
'superficial we are objective' is the wordplay.
I cannot quite see how this works, but
'we' could be 'us' and 'us' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'though' is the link.
Can you help me to learn more?
(Other definitions for thus that I've seen before include "an original Christmas gift" , "'So, therefore (4)'" , "Shut (anag.)" , "Therefore, hence" , "It follows" .)