It's the C in the Video Recorder Known as a VCR
This page is the CodyCross answer for the clue below from Treasure Island, Group 1035, Puzzle 1 (Lioness of Brittany).
Question is: It's the C in the Video Recorder Known as a VCR
and the answer is: CASSETTE
Word Meaning:
CASSETTE — A small flat case containing magnetic tape on two reels, used to record and play back audio and video material.
Definitions from Wiktionary.