Put an end to good deal (4)
I believe the answer is:
slew
I believe this is a double definition.
'put an end to' is the first definition.
(archaic past tense of 'slay')
'good deal' is the second definition.
(I know that good deal can be written as slew)
(Other definitions for slew that I've seen before include "Move obliquely or sideways, often losing control" , "Large amount - killed intentionally" , "Twist sideways" , "Quite a number" , "Large number -- killed" .)