ACROSS
 1 Some carpenters, perhaps, but not joiners, aren’t very pleasant superficially. (5)
 4 See 12 across
11 In making a strict diagnosis, you might consider it belonging to the stomach. (7)
12 and 4 Ring-maker. (7,6)
13 Revolving digits. (9)
14 Following exercise? (5)
15 Day-old play, evidently. (4,9)
17 Stand up and be counted, with less of eastern revolutionary movement. (6,7)
22 See 6 down
24 With broken outer ends, things go to pot this way. (3,2,4)
25 Implying too much of the type to spread and take possession. (7)
26 A beetle couldn’t be a cockroach! (7)
27 It’s due, perhaps, to be carried out. (6)
28 Smetana’s was bartered. (5)
 
DOWN
 2 Coins, as flipped in a game. (7)
 3 Probably involves squares, though called figures here. (4,5)
 5 Tie in a race, at least one in a race. (5)
 6 and 22 across Just a drop of water, or a lot more. (7,5)
 7 When not on foot, I would shortly get in the circle. (6)
 8 One entrance might be stone. (5)
 9 Something unplanned and unpleasant leads to lying—but such a type might be expensive to cover. (8-5)
10 In the ring, they fling this in a way that’s mildly terrific! (13)
16 Asking for Juncus to get here as quickly as possible? (4,5)
18 A foreigner in a little way outstanding. (7)
19 Bedelia is made up, but certainly not as an Early Bird! (3-4)
20 A loud way to come across, and bear the expense. (6)
21 Our present year and all our years might be proverbial. (5)
23 Possibly good material for Koussevitzky. (5)