Made a serious mistake or made one's way blindly (9)
I believe the answer is:
blundered
'made a serious mistake or made one's way blindly' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for blundered that I've seen before include "Made a stupid error" , "Committed a faux pas" , "Slipped" , "Made a serious mistake or made one's way blindly" , "Moved about awkwardly and clumsily" .)