Stressful moment fixing fences (4-6)

I believe the answer is:

nail-biting

I'm a little stuck... Click here to teach me more about this clue!

'stressful moment fixing fences' is the definition.
I can't tell whether this definition defines the answer.

'moment fixing fences' is the wordplay.
'moment' becomes 'bit' (synonyms).
'fixing' becomes 'nailing' (I've seen this before).
'fences' means one lot of letters goes inside another (inserted letters are fenced off).
'bit' put inside 'nailing' is 'NAIL-BITING'.

Can you help me to learn more?

I've seen this clue in The Telegraph.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.