---

All answers having "Extension" as clue:

3 Character Answers:

---

ARM

ELL

LIE



4 Character Answers:

---

CORD

LIMB

WING



5 Character Answers:

---

ADDON

ANNEX

CACAO

LAPUP

PHONE

SWEDE



6 Character Answers:

---

ANNEXE



7 Character Answers:

---

RENEWAL