Trust more, certainly (9)
I believe the answer is:
doubtless
This clue might be a double definition.
'trust more' is the first definition.
Both the answer and definition are adverbs. Maybe you can see an association between them that I don't see?
'certainly' is the second definition.
(I've seen this before)
Can you help me to learn more?
(Other definitions for doubtless that I've seen before include "Assuredly" , "Unquestionably" , "Positive" , "Probably, certainly" , "of course" .)