### Clue: Cover with solid pace, injecting velocity to avert century (4)
### Answer: PAVE 
 ### Explanation: Definition: Cover with solid
 "pace" **containing**(injecting) V(abbrev. for "velocity", in physics) **minus**(to avert) "c"(abbrev. for "century"/100 years).
Defn: …, as with, well, a pavement.