Everyman 3407 Do not get!

[Gavmacp]

10a. Principal boy appearing in theatre-in-tHE-ROund (4). Answer HERO but why? I obviously see the hero bit in clue.
12a. Books one consultation, primarily about the ear (4). Answer OTIC get the IC but why book= OT.
8d. Gun down a crocodile to show off (5,1,4). Answer SHOOT A LINE but why crocodile?

[dr b]

books = Old Testament

crocodile, "A long line or procession of people (especially children) walking together"

[dr b]

hero, "The principal male character in a novel, poem, or dramatic presentation" - so principal boy?

[Lie-in King]

Principal boy = male hero in a panto

O(ld) T(estament)...

http://dictionary.ref....com/browse/crocodile

^ Def. 4 (file = line)

[Gavmacp]

Thank you! Not too bad this week. I like to understand the answers.