1: Fashionable journalist coming back after battle (1,2,4)
4: Mad? O, yes! Mad dog! (7)
7: Long Rhine sequence in Wagner's work (9)
9: Soldier shelled in song from the past (5)
11: Height is equal to three-fifths of the first one (3)
13: Capital investment producing hard faces (9)
15: Demonstrated the way in which to keep poles apart (5)
16: One giving evidence, if ignored, would be more snappish (9)
17: Archaeopterix? Maybe I err badly (5,4)
20: Raptor is well under par (5)
21: Nixon-Reagan era political appointments (9)
22: Rohmer hiding unit of Resistance (3)
23: Zantac's first in things to buy for composer (5)
24: Dressing of malt and beans to make horse tender (9)
26: Hold torn veil held by busy worker (7)
27: Sort of collection to compose print (7)