Not affected as outsiders in race (7)
I believe the answer is:
sincere
'not affected' is the definition.
'as outsiders in race' is the wordplay.
'as' becomes 'since' (I've seen this before).
'outsiders in' suggests removing the centre.
'race' with its middle taken out is 're'.
'since'+'re'='SINCERE'
(Other definitions for sincere that I've seen before include "Unfeigned, genuine" , "(Of person) genuine" , "True" , "Not hypocritical" , "Free from deceit" .)