Convey what wrong answers may do (3,6)
I believe the answer is:
get across
'convey' is the definition.
(to get something across is to communicate it)
I can't explain the remainder of the clue.
(Other definitions for get across that I've seen before include "Manage to communicate" , "Clearly explain" , "go over viaduct, say" , "Express" , "Go over - explain" .)