Doubt of struggling atheist one finds acceptable (10)
I believe the answer is:
hesitation
'doubt' is the definition.
(thesaurus)
'struggling atheist one finds acceptable' is the wordplay.
'struggling' is an anagram indicator (I've seen this in other clues).
'one' becomes 'i' (Roman numeral).
'finds' says to put letters next to each other.
'acceptable' becomes 'on' (I've seen this in other clues).
'atheist' with letters rearranged gives 'hesitat'.
'hesitat'+'i'+'on'='HESITATION'
'of' acts as a link.
(Other definitions for hesitation that I've seen before include "indecision" , "Pause" , "Wavering" , "Reluctance" .)