Wrong answer — subsequently repeated in second test (6)
I believe the answer is:
astray
'wrong' is the definition.
(going astray is going wrong)
'answer subsequently repeated in second test' is the wordplay.
'answer' becomes 'a' (abbreviation eg in Q and A).
'subsequently repeated' becomes 'a' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' means one lot of letters goes inside another.
'second' becomes 's' (common abbreviation).
'test' becomes 'try' (synonyms).
's'+'try'='stry'
'a' going into 'stry' is 'stray'.
'a'+'stray'='ASTRAY'
(Other definitions for astray that I've seen before include "Away from the right path like a satyr (6)" , "Up the garden path?" , "wrong way" , "Missing, lost" , "Off the correct path" .)