Happen to come to mind (5)
I believe the answer is:
occur
I believe this is a double definition.
'happen' is the first definition.
('occur' can be a synonym of 'happen')
'come to mind' is the second definition.
(thesaurus)
'to' is the link.
(Other definitions for occur that I've seen before include "Spring to mind" , "crop up" , "Happen - to come to mind" , "Come to pass" , "appear" .)