Head away from most dangerous mountain (7)
I believe the answer is:
everest
'mountain' is the definition.
(Mount Everest)
'head away from most dangerous' is the wordplay.
'head away from' means to remove the first letter (I've seen 'heading away from' mean this).
'most dangerous' becomes 'severest' (I've seen this before).
'severest' with its first letter taken off is 'EVEREST'.
(Other definitions for everest that I've seen before include "Highest peak" , "Where Hillary was" , "One conquered in 1953" , "Mount, climbed 1953" , "Highest Himalayan mountain" .)