---

All answers having "Speculate" as clue:

3 Character Answers:

---

BET



4 Character Answers:

---

RISK



5 Character Answers:

---

GUESS

OPINE

WAGER



6 Character Answers:

---

GAMBLE

WONDER



7 Character Answers:

---

DARESAY

PRESUME

SURMISE



8 Character Answers:

---

THEORISE

THEORIZE