Crows make a killing (6)
I believe the answer is:
murder
I believe this is a double definition.
'crows' is the first definition.
(I've seen this before)
'a killing' is the second definition.
(I know that murder is a type of murder)
'make' acts as a link.
(Other definitions for murder that I've seen before include "Slay; bump off" , "Deliberate homicide" , "See 16" , "Kill" , "Voraciously consume" .)