Sunday Times Prize Crossword 4671 Sunday December 6Th 2015

[mercedita]

Sorry to be late with these: please can someone parse the following 3?
18A Snake cut in half by gunners in empty tower (8). Ziggurat is the tower but how?
21A Affectionate wizard's fight to hold on (13) Demonstrative is Affectionate but I can't see the rest.
2D In reporter's role, cut grass with sailor (9). Narrating has rating for a sailor but I can't get the 'cut grass'.
Thanks (If anyone's about!)

[Lie-in King]

18a Ziggurat - 'zig(-zag)' (snake, half) + 'R(oyal) A(rtillery)' (in) 'gut' (empty)
21a Demonstrative - 'demon' (wizard; ace) + 'strive' (fight, to hold) 'at' (on)
2d Narrating - 'nar(k)' (grass, cut) + 'rating' (sailor)

[Ouzel]

2d Grass = Nar(k) - an informer

[Mamyalynne]

18 Zig (zag) + Gut round RA

[scorpiojo]

Zig (snake) gut (cut) RA (Royal Artillery)
Demon + strive + at(to)
Nar(k) rating

[vetuste_ennemi]

zig[zag] + g(RR)ut

[mercedita]

Gosh! Thanks everyone! I'm amazed you are up and about at this time! Thanks so much for your help. Really appreciate it. :-)