What does the cryptic crossword clue "Largely hair-raising mountain route? (3)" mean?

The definition is "mountain route". The wordplay uses a reversal. LOC (reversal="LOC") = COL; definition: "mountain route?" The answer is COL.

Largely hair-raising mountain route? (3)

Times Cryptic #28851 | 24 Down | 2024-02-28 flower