Vacuous reverend injecting whizz was rushing (5)
I believe the answer is:
raced
'was rushing' is the definition.
(race can mean to rush around)
'vacuous reverend injecting whizz' is the wordplay.
'vacuous' means to remove the middle letters.
'injecting' means one lot of letters goes inside another.
'whizz' becomes 'ace' (synonyms).
'reverend' with its middle removed is 'rd'.
'rd' going around 'ace' is 'RACED'.
(Other definitions for raced that I've seen before include "Competed" , "Went quickly round" , "Sped" , "bolted" , "went at speed" .)