ACROSS
 1 As old Marley was to begin a favorite Carol? (4,2,1,8)
 9 Similar to a mimic? (7)
10 One doesn’t reputedly make a summer drink this way. (7)
11 To tear to pieces in turn? (6)
12 Snow-bound writer. (8)
14 They might be crossed at entrances. (10)
15 Have an inclination to be other than fat? (4)
17 24 down obviously makes money! (4)
19 They couldn’t have more than nine commandments left to break! (10)
22 Treated like a king. (8)
23 Genus of the carrot and hemlock family as an ingredient of Rose’s Elixir. (6)
25 Going by what you already know, this ill-fitting pair took Rio by storm. (1,6)
26 Not a nice word to apply to one in the building brotherhood! (7)
27 A sign that someone is against the Wearing of the Green? (4,3,3,5)
 
DOWN
  1 Help to get it up with a rigorously discriminating grade—it might be attached to a letter. (11,4)
 2 The kind of man Gunga Din was might be of some aid. (7)
 3 It might be for gold. (4,4)
 4 Tools about which things might 11. (4)
 5 Early and late, one isn’t this. (2,8)
 6 They might 11 with spit. (6)
 7 Exceeding all others in past history. (3-4)
 8 Drop down on the target. (5,4,6)
13 Does it involve having courage enough to do away with investment? Things stand out in it. (4,6)
16 Getting even? (8)
18 Attila was one of God, but beat. (7)
20 They sang about her as being dear and sweet. (7)
21 Miss Novak has on nothing but a loose robe! (6)
24 This writer sounds as though he’d either have to serve at court or be burnt! (4)