ACROSS
1 God no longer (4,2)
#4 Mode of transport for an electron density of 1001 (9)
#6 No hit out (4)
7 Jill's brother is a stranger (3,3'1,4,4)
12 Wasn't Clyde Narain a mammal? (7,3)
14 Insect killer above the red square (4,4,6)
15 Helminthiasis (5)
16 Found in my stomach (4)
17 He keeps punching the pavement (6,7)
19 How to get into the hairless Sumerian city (6'1,4)
20 A rubber dog's toy shaped like a mule (6,4)
21 Excavator aroused abnormally (5,5)
23 Last dream (5,7)
27 What a smell! (4)
29 Iranian heir (6,2,6)
31 Gracelands former occupant endlessly messed up (8,4)
36 Young man with a preference for parchment (8)
38 It's the bola I'd tangled up (6)
41 Lucifer Lacrimosa (5,3,3)
43 Grey (5,3,5)
45 Proxemics offenders (5,8)
46 The grassy knoll won't tell (6,4)
48 Bad mood (4)
49 It's not doubling time (4-4)
50 Harry Potter's canine omen buys tickets in the US (4,8)
51 Seen in his naked form (5)
52 Aves aggrieved (5,5)
DOWN
1 John Wayne takes extreme action (4,5)
2 Mr Astley takes chances (4,9)
#3 Over-enthused about icing a cake (9)
5 Overlooked planets (9,6)
8 Phoning about your shift (4,2,4)
9 Watery brontide (5,7)
10 Tents messed up by a Sumerian goddess (6)
#11 Attempts an alternative to coffee, initially confused (6)
13 It sounds like hay for a priest (6,6)
18 Podiatrist's problem with a count (6,3,4)
22 James Annelida (9,3)
24 They play for the director of a Life of Pi (7)
25 £1000 robbery without thinking (5,5,4)
26 You can't have it, that brush (11)
28 Bill is ready to fly (3,3,5)
30 A tripping skydiver does it (7)
32 It looks like Mr Hanks does hair (4,6)
33 Instructs the avian limb (4,9)
34 The french leave a cricketer (4,6)
35 Tangled ropes (5)
37 Too many sweets in your pocket (5,5)
39 Smaug + Tiamat (6,6)
40 It goes round your pebble (4,4)
42 Outcome of a religious service (4,6)
44 Simon Cowell (6)
47 Torn, broken (4)
Hopefully there aren't too many here that people find obscure or ambiguous. If people are struggling, I might add release dates.