Incendiarism against right saw off nominee initially (5)
I believe the answer is:
arson
'incendiarism' is the definition.
(synonyms)
'against right saw off nominee initially' is the wordplay.
'initially' indicates taking the first letters.
The initial letters of 'against right saw off nominee' is 'ARSON'.
(Other definitions for arson that I've seen before include "Pyromaniac crime" , "Malicious burning to destroy property" , "burning problem" , "Be pettish" , "Fire-lighting crime" .)