Get hold of good tool (5)
I believe the answer is:
grasp
'get hold of' is the definition.
(I've seen this in another clue)
'good tool' is the wordplay.
'good' becomes 'g' (abbreviation).
'tool' becomes 'rasp' (rasp is a kind of tool).
'g'+'rasp'='GRASP'
(Other definitions for grasp that I've seen before include "Support; rugby player" , "Lay hold of" , "Catch on" , "Keep tight hold" , "Understand (the point)" .)