Near disaster with sextet in canyon (6)
I believe the answer is:
ravine
'canyon' is the definition.
(I know that canyon can be written as ravine)
'near disaster with sextet' is the wordplay.
'disaster' indicates an anagram.
'with' means one lot of letters goes inside another.
'sextet' becomes 'VI' (synonyms).
'near' with letters rearranged gives 'rane'.
'rane' enclosing 'vi' is 'RAVINE'.
'in' is the link.
(Other definitions for ravine that I've seen before include "Defile" , "Steep-sided gorge" , "Type of gorge" , "Deep narrow valley" , "Deep narrow gorge between mountains" .)