Doubting cost in wrangle with Silver Top (8)
I believe the answer is:
agnostic
'doubting' is the definition.
(someone unsure on the topic of religion)
'cost in wrangle with silver top' is the wordplay.
'wrangle' indicates an anagram.
'with' is an insertion indicator.
'silver top' becomes 'ag' (I can't justify this - if you can you should believe this answer much more).
'cost'+'in'='costin'
'costin' is an anagram of 'nostic'.
'nostic' placed around 'ag' is 'AGNOSTIC'.
Can you help me to learn more?
(Other definitions for agnostic that I've seen before include "Religiously non-commital" , "One who is undecided" , "Person who doubts the existence of God" , "Coasting as one who believes the mind cannot know anything of a god" , "He finds it difficult to believe" .)