2100: Mask

Each of eighteen clues contains one misprinted letter in the definition part. Corrections of misprints spell a four-word phrase which alludes to the unclued lights, indicating the position of one of them in relation to the others. One unclued light is  hyphened; elsewhere, ignore an accent.
 
Across

1 Neat section, last of four in colour (6)
7 Hypersensitive airman carrying hat (6)
13 Money returned one hour before denial (5)
15 Offhand treatment of urban movie lacking love (9, two words)
16 Sties left covered with rubbish (6)
22 Rudiment in article with new angle (6)
24 See star prepared by right to be champion (8)
28 Moth down under clothes (3)
32 Date set by sailor with a clock (8)
34 Capital reserve cut by nation (6)
35 Massages completely reversing strain (6)
37 Kind round in pub with good club (7)
39 Fanatic in quest partly numbed (6)
42 Artist developed tale in part of poem (9)
43 Approve conclusion of nurse about injection (5)
45 Navy led by king in state of agitation scattered (6)
46 Big hope to retire with cry of joy (6)
 
Down

1 Producer of terse exclusive without heart (4)
2 Vote supporting scheme involving hospital and a bond (7)
3 Grand in manner, elevated poet (4)
4 Grain kernel broken by sheep (7)
5 Smell motor quickly (8)
6 Fishes disappear in steamer (6)
8 Park, tense, on edge (4)
9 Upright and holy, worried about trap (8)
10 Meal without depth congealed (5)
11 Rustic colt may not run badly (10)
14 Confused legend chaotically packed with colour (9)
17 Remainder including gold repaid (6)
18 Raising pressure in compound with suggestion (9)
19 Bushes boozer scanned, befuddled (10, two words)
23 Bring down doctor, disrupting peace (6)
26 Joint, eaten in error, containing alien material (8)
30 End up accepting literature I forge (7)
31 Droop, losing first race (7)
33 Vitamin container, holding tiny amount, unfinished (6)
36 Lifted fast, keeping active (5)
41 For example, mother provides puzzle...