Best tool (4)
I believe the answer is:
pick
I believe this clue is a double definition.
'best' is the first definition.
(I've seen this before)
'tool' is the second definition.
(pick is a kind of tool)
(Other definitions for pick that I've seen before include "flower" , "Choose - ground-breaking instrument" , "Select - ground breaker" , "Choose - tool for breaking up ground" , "tool - it breaks" .)