12 ac) Unusually, GIs license ancient peace slogan (7,2,6).
21 ac) Doubt expressed perhaps, that marksman will succeed in opera (3,5,3,4).
Sorry to sound petulant, frustration showing.
Icheria you have the wrong literal. The definition is 'doubt expressed, perhaps' not 'opera'. You can stop sighing; there is no error, just a very oblique clue as many are this week.