Crossword Genius

For Frenchman, extremely small lock (5)

Ross

I believe the answer is:

tress

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

'lock' is the definition.
(I've seen this before)

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for tress that I've seen before include "Long lock or plait of hair" , "Bit of hair" , "Rests (anag.)" , "is a bit of a shock" , "Braid of hair" .)

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.