Keep supply of broth (5)
I believe the answer is:
stock
I believe this is a triple definition!
'keep' is the first definition.
(I've seen this before)
'supply' is the second definition.
(stock can mean a supply or reserve)
'of' is a link.
'broth' is the third definition.
(I know that broth can be written as stock)
(Other definitions for stock that I've seen before include "Cattle" , "Material in store" , "Equestrian tie" , "Neck garment" , "Consomm-like liquid" .)