CCCWC July competition voters’ comments on Clue no. 12

A clue to SHOESTRING.
2 comments refer to this clue (from 2 competitors, 0 others)

Here is the text

Comments on the clue

1.	But how do you get from the homophone to 'shoestring'? There is nothing in the clue that indicates this.
2.	Nice variation, but then 'tiers' is in the plural?