Easy as abc

Across

1Modifier of verb or adjective (6)
5A measure of how likely it is that some event will occur (6)
10Draw air into, and expel out of, the lungs (7)
11A system of conveying mail by aircraft (7)
12Marine mollusks having a rough irregular shell (6)
15At or near the north pole (6)
16Virgin Mary (7)
17The cry of a donkey (4)
18A useful or valuable quality (4)
19Periodically accumulated over time (7)
20Dollar bill (4)
22Call in an official matter, such as to attend court (4)
25The playing of a game of tenpins (7)
27A Scandinavian kingdom (6)
28The act of apprehending (6)
31Underground stem (7)
32A small four-stringed guitar (7)
33Sorrowful through loss or deprivation (6)
34Act in retaliation (6)

Down

2Precedes diving and fishing (4-3)
3Regard highly; think much of (6)
4Cattle that are reared for their meat (4)
5Burrowing marine mollusk living on sand or mud (4)
6Northern or southern lights (6)
7Any tangible movable property (furniture or domestic animals or a car etc) (7)
8To soak up a liquid (6)
9Child's building toy (6)
13Omnivorous nocturnal mammal (7)
14Refined or imposing in manner or appearance; befitting a royal court (7)
15Sends or receives radio or television signals (7)
20A small informal restaurant; serves wine (6)
21A long narrow depression in a surface (7)
23A large mass of ice floating at sea (7)
24The principal dish of a meal (6)
25Earlier in time; previously (6)
26Popular game bird (6)
29Penny (4)
30An indication of radiant light drawn around the head of a saint (4)