Exhort (4)
I believe the answer is:
urge
'exhort' is the definition.
(I know that exhort can be written as urge)
This is the entire clue.
(Other definitions for urge that I've seen before include "Persuade - proclivity" , "Compulsion; egg on" , "Impel - impulse" , "Incite to action" , "Advise strongly or prod" .)