Suppose to be deliberate (5)
I believe the answer is:
think
I believe this is a double definition.
'suppose' is the first definition.
('think' can be a synonym of 'suppose')
'be deliberate' is the second definition.
(thesaurus)
'to' is the link.
(Other definitions for think that I've seen before include "Believe" , "Imagine" , "Ponder" , "Use one's mind" , "Meditate" .)