---

All answers having "Futile" as clue:

4 Character Answers:

---

IDLE

VAIN

WILT



5 Character Answers:

---

NOUSE

NOWIN



6 Character Answers:

---

NOHOPE

OTIOSE



7 Character Answers:

---

AIMLESS

OFNOUSE

USELESS



8 Character Answers:

---

BOOTLESS



9 Character Answers:

---

POINTLESS



10 Character Answers:

---

UNAVAILING



11 Character Answers:

---

INEFFECTUAL