Choose the best digging tool (4)
I believe the answer is:
pick
This clue is a triple definition!
'choose' is the first definition.
(I know that pick is a more specific form of the action choose)
'the best' is the second definition.
(the best possible pick or selection)
'digging tool' is the third definition.
(tool used for digging)
(Other definitions for pick that I've seen before include "Select - ground-breaking tool" , "Choice" , "Pluck" , "Choose - tool for breaking up ground" , "Play guitar" .)