Cryptic crossword No 3,937

Across

1. View internals of servants after surgical operation (7)
2. Inside of hell, fiend initially becomes saint at last (8)
3. Devour loaves of sourdough, perhaps after removing crust (4)
4. Rest of linseed oils finally manufactured (8)
5. Show has one fellow boring extra (6)
6. Doctor cut skin in fight (6)
7. A cane caught grandma's head exactly (6)
8. Opera by the French with a fixed growth (2,5)
9. Sprinted with physician's authorization breaking race record (10)
10. Regularly passing Estonian mountain (4)
11. Cloudy stretch in our universe (5,3)
12. Essentially probe dead in physical test proving misconduct (6)
13. Sally sees E.T for the content (3,5)
14. Create a union hiding social worker being sought for by the police (6)
15. Briefly take in ecosystem's overwhelming unique physical features (10)
16. Groups of sailors escaping from trap in voyage (6)

Down

1. Way to make earring? (9)
2. Review is written up on paper (4)
3. Energetic detective tailed the mob back inside (7)
4. Occasionally covering up nervier NATO incident (5)
5. English university fixed up window (4)
6. Mother's holding son in crowd (4)
7. Entrap a meerkat, gutted to be arranged flat (9)
8. Idled with tea supply presented (8)
9. Fellow tenant originally housing vacated room to man essentially unemployed (7)
10. Boredom at work, us both during speech (5)
11. Boldly display special whip (6)
12. Evil cops close to planting piece of evidence (4)
13. Greatly appreciated gym class (4)
14. Floors with remains of fallen trees (6)
15. Hand out each of the books (5)
16. License from nosy ass-kisser cops held up (3-2)
17. Spot field devoid of nitrogen (4)
18. Provide an alibi to leader of riots charged as supporting guy (5,3)