So slight as to seem less than nothing? (4)

I believe the answer is:

thin

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

'so slight' is the definition.
'thin' can be an answer for 'slight' (similar in meaning). I am not certain of the 'so' bit.

'to seem less than nothing?' is the wordplay.
'THIN' is hidden within the letters.
But, I'm not sure how the hidden word is indicated.

'as' is the link.

Can you help me to learn more?

(Other definitions for thin that I've seen before include "Watered down" , "Lean; narrow" , "Flimsy" , "Superficial" , "(Of smile) weak, forced" .)

I've seen this clue in the Evening Standard.

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.