Ably and supply (4)
I believe the answer is:
well
I believe this is a double definition.
'ably' is the first definition.
(to do something well is to do it ably or skilfully)
'supply' is the second definition.
(well can mean a supply or reservoir)
'and' acts as a link.
(Other definitions for well that I've seen before include "indeed" , "Lift-shaft" , "Healthy; extremely" , "Borehole" , "Healthy - water supply" .)