Measure pay (4)
I believe the answer is:
foot
I believe this is a double definition.
'measure' is the first definition.
(foot is a kind of measure)
'pay' is the second definition.
(footing is a kind of paying)
(Other definitions for foot that I've seen before include "Imperial distance" , "An imperial length or body part" , "Twelve inches" , "See 24" , "12 inches" .)