Undersides of feet (5)
I believe the answer is:
soles
'undersides of feet' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for soles that I've seen before include "Parts of shoes" , "They're always under one's feet!" , "Undersurfaces of feet" , "Undersides of feet" , "Fish; bottoms of feet" .)