Turns out these puzzles are tricky! Hopefully the clues for this one are a bit easier. Hint if you're stuck: This puzzle involves rebuses. To enter multiple letters into a cell, use the Escape key (on computer) or the More menu (on phone).
That's the first one I didn't have to reveal most of the puzzle. Had trouble with 3a because I didn't realize it could be one word split in two. Great puzzle though!
I did originally have "How one climbs a rock face or hauls a rope", but opted for the clue you see in the puzzle because:
Most definitions online seemed to limit the term to purely rope-based activities, and
As someone who used to rock climb, I remember it much more as HANDOVERFOOTOVERHANDOVERFOOT (unless you've got arms of steel and are showing off, in which case, kudos!)