Promise from Sean as cur moved (9)
I believe the answer is:
assurance
'promise' is the definition.
(assurance is a kind of promise)
'sean as cur moved' is the wordplay.
'moved' indicates anagramming the letters.
'sean'+'as'+'cur'='seanascur'
'seanascur' with letters rearranged gives 'ASSURANCE'.
'from' is the link.
(Other definitions for assurance that I've seen before include "Confidence; security" , "Cure an ass of a feeling of certainty" , "Certainty; life insurance" , "Confidence, certainty" , "Word given" .)