The ornamental design for a sole for footwear, as shown and described.
1. Sole for footwear
1.1 : Bottom
1.2 : Front
1.3 : Top
1.4 : Right
1.5 : Back
1.6 : Left
The broken lines in 1.3 depict portions of the sole for footwear and form no part of the claim. The light gray portions inside the broken lines form no part of the claim.