Mark on church left by Yankee? Not at all (8)
I believe the answer is:
scarcely
'not at all' is the definition.
(thesaurus)
'mark on church left by yankee?' is the wordplay.
'mark' becomes 'scar' (synonyms).
'on' says to put letters next to each other.
'church' becomes 'CE' (abbreviation for Church of England).
'left by' becomes 'l' (I've seen this in other clues).
'yankee?' becomes 'Y' (phonetic alphabet: alpha, bravo, charlie etc.).
'scar'+'ce'+'l'+'y'='SCARCELY'
(Other definitions for scarcely that I've seen before include "Only just or hardly even" , "Barely, hardly" , "Not quite" , "Surely not" , "Almost not" .)