Based on the clue 'a cluster of people or more commonly a flock of ge...', what is the answer?

Based on the clue 'a clue to umberto ecos murdered monks they have t...', what is the answer? Based on the clue 'a clumsy mistake such as one selected by dick clar...', what is the answer? What is referred to by 'a clumsy social error'? Based on the clue 'a cluster headache may center in these religious r...', what is the answer? Based on the clue 'a cluster of sunbathers may induce it', what is the answer? Based on the clue 'a cluster or hand of this fruit consists of 10 20 ...', what is the answer? Based on the clue 'a cntrctd form of a wd or phrs frm the ltn for shr...', what is the answer? Who performed with 'a co biography of these two men tells of the battle of waterloo and the great commanders who fought…