Part of foot to move slowly (4)
I believe the answer is:
inch
I believe this is a double definition.
'part of foot' is the first definition.
(I've seen this before)
'move slowly' is the second definition.
(I've seen this before)
'to' is the link.
(Other definitions for inch that I've seen before include "Creep, edge" , "Move along gradually" , "Twenty-five point four millimetres" , "Twenty five point four millimetres" , "Two point five four cm" .)