1: Tranquillises extremely senile escorts (7)
4: Weapon company accommodating listener (7)
7: Guess what the benighted marksman did? (4,2,3,4)
9: Rocks lure a breeding fish (4,9)
11: Zantac's first in things to buy for composer (5)
12: Deep dirge played for one of unimpeachable heritage (9)
14: No government lawyer's thrilled to display being agreeable (3,6)
16: First company get rest when they come to a stop. (5)
17: Asian river ordeal; it's upset manufacturer (13)
19: Repeated note to help player? (6-7)
20: Rhyme in Old English to run the show (7).
21: Crazy macabre American authors outside making perfumed hair applications (7)