Increase the speed of (an engine) (3)
I believe the answer is:
rev
(Other definitions for rev that I've seen before include "vicar?" , "Cleric" , "One turn of an engine, in short" , "Accelerate (abbrev.)" , "Clergyman, or woman (abbr)" .)
I believe the answer is:
rev
(Other definitions for rev that I've seen before include "vicar?" , "Cleric" , "One turn of an engine, in short" , "Accelerate (abbrev.)" , "Clergyman, or woman (abbr)" .)