1: Ten orphans pointlessly wander around the Acropolis. (9)
2: Edits Russian performances (7)
3: Frozen awkwardly, i.e. a tin man (9)
4: Drank up in station (5)
5: Got off the coach tired, on Eastern time (9)
7: Will, in the past, cried out 'timber' (5)
9: Take Chair in university (3)
12: Game for artist holding tip of paintbrush right (4,5)
13: Central Slovak airport damaged 16-down (9)
14: Prune plums for reserves, once more (9)
16: Against trailing machine after cropping wine (7)
17: Solitary one finally putting me back in service (7)
18: Chiefly toast mother country (5)
19: Oxygen is pretty amusing. (3)
20: Path of planet - or particle (5)