### Clue: Free to engage drive that elevates site machine (6)
### Answer: DIGGER 
 ### Explanation: Definition: site machine
 **Reversal of**(… that elevates, in a down clue) [ RID(to free of, eg. pests) **containing**(to engage) EGG(to drive;to urge on) ].
Defn: Machine at a work site.