Implement as well left (4)
I believe the answer is:
tool
'implement' is the definition.
(I know that implement can be written as tool)
'as well left' is the wordplay.
'as well' becomes 'too' (both can mean 'also').
'left' becomes 'L' (common abbreviation).
'too'+'l'='TOOL'
(Other definitions for tool that I've seen before include "Device, implement" , "Maybe saw" , "Drive motor skilfully" , "Implement - agency" , "Appliance" .)