Motives, reasons (6)
I believe the answer is:
causes
I believe this is a double definition.
'motives' is the first definition.
(I've seen this in another clue)
'reasons' is the second definition.
(the reasons for something)
(Other definitions for causes that I've seen before include "Factors" , "Brings" , "Reasons why things happen" , "They bring about effects" , "Gives rise to -- crusades" .)