Last corner syndrome again. 21a. Back secured by cable in the morning, left space (4,4) ?A??/?O?M, 15d. Musical drama in shelter gets band together (9) C?O???A??. Finally, 28a. Cut on end of nose is serious (6) ?E???E. Explanations, please.
Oops....I think you mean cooperaTe and not cooperaGe. 'Cote' is a small shelter for animals. Thus the definition 'band together' makes sense: band together-cooperate.