2141: Megacant

The unclued lights (all but two of two words) are of a kind, listed in Chambers 2011. Elsewhere, ignore one accent.
 

Across

 
1    Race to leave car in protected area (12, two words)
10    Regular car rides to Irish peninsula (4)
12    Able to include one opposing support (10)
14    Everything’s satisfactory returning the acacia (3)
17    Pillar of Hercules unknown in Gaelic Scotland, on reflection (5)
18    Reversion to type in songbird, head to tail (7)
22    Phoenician goddess is with husband, 28 (6)
24    Bird in river and lough (5)
29    Diminutive confection without number, it may seem (5)
31    Body initially pivoting on track two for starters (6)
34    Frothy and rancid, top changing (6)
38    Apparently singular bar on sword (5)
39    Mayflies which have little worth (8)
40    Individual loner at heart (3)
41    Investment opportunity no medic arranged without enjoyment (10, two words)
42    God’s painful back (4)
43    Businessmen will not disclose these, as street cred dissolves (12, two words)
 

Down

 
2    Artistic positions which, in France, an artist and Queen hold (10)
3    Segregate one, before such an advanced hour (7)
4    Shellfish brought up from Lancaster Canal (5)
5    Mineral (hard), yet in crumbly form (9)
6    Spoil piece of work King rejected acquiring artworks (6)
7    Bird always up around early evening (5)
8    Jumbos at springs (4)
9    Public announcement of concert on a guilt trip (12)
11    Daughter always having light dress for time at work (8, two words)
16    Nelson = 40 x 3 (3)
19    It’s not very often you see this railway accepting rebuilt train that’s not new (6)
20    Fine, but not well despite appearances (6)
23    Aunt Rose’s irregular time of sexual inactivity (9)
25    Poorly realigns US indicator (8)
28    Sailor’s short dance (7)
30    Thought of river and sea (6)
33    Senior magistrate twirling rope round horse’s head (5)
35    ‘There is no letter more common ……..’