Arch support
'arch support' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for insole that I've seen before include "Padding in a shoe" , "Part of a shoe or boot" , "support for rambler, perhaps" , "Lesion in part of foot" , "Inner part of shoe" .)
'arch support' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for keystone that I've seen before include "Important piece at apex of arch" , "Central part of arch" , "Something on which all else depends" , "Central principle of a policy" , "Central block at the top of an arch" .)