Force of spirit exorcist initially left behind (5)
I believe the answer is:
impel
'force' is the definition.
(synonyms)
'spirit exorcist initially left behind' is the wordplay.
'spirit' becomes 'imp' (I have seen 'Evil spirit ' mean 'imp' so perhaps 'spirit' could also mean 'imp').
'initially' indicates taking the first letters.
'left' becomes 'l' (common abbreviation).
'behind' is a charade indicator (letters next to each other).
The first letter of 'exorcist' is 'e'.
'imp'+'e'+'l'='IMPEL'
'of' is the link.
(Other definitions for impel that I've seen before include "Drive or coerce" , "Spur on" , "Urge or propel" , "Urge or drive to do something" , "Force forwards" .)