All answers begin with 'sub'

-1. SUB + posture = Matter. 9 letters

-2. SUB + a seaman = Underwater. 9

-3. SUB + to combine = To go under the surface. 8

-4. SUB + a piece of land = To deduct. 8

-5. SUB + to message someone using a cellphone = Nuance or undertone. 7

-6. SUB + a citrus fruit = Transcendent. 7

-7. SUB + a letter = Docile. 10

8. SUB + edge = To sink. 7

-9. SUB + harden = Part of a bigger group. 6

-10. SUB + quest = The act of yielding to another. 10

10. Submission 😊

1. substance

First and last done. Merci.

5. subtext

Thanks jb.

6. sublime

Merci michele.

3 - submerge

7. submissive

4. Subtract

Well done.

2. submarine

9. subset

Thanks.

8. subside