One reaching across may get a wrench (7)
I believe the answer is:
spanner
This might be a double definition.
'one reaching across may get a' is the first definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'wrench' is the second definition.
(synonyms)
Can you help me to learn more?
(Other definitions for spanner that I've seen before include "Nut turner" , "Nut-turning tool" , "Bolt tightener" , "Tool for gripping and turning" , "Hand tool to grip and turn" .)