---

All answers having "Calm and collected" as clue:

4 Character Answers:

---

COOL



6 Character Answers:

---

SEDATE

SERENE



7 Character Answers:

---

CORDIAL

HOLLERS



8 Character Answers:

---

APERITIF

INREPOSE



9 Character Answers:

---

NERVELESS



10 Character Answers:

---

COOLHEADED



13 Character Answers:

---

SELFPOSSESSED