What does the cryptic crossword clue "Quartz watch that doesn't look real? (5,3)" mean?

The wordplay uses a charade (building blocks). GLASS (synonym="quartz") + EYE (synonym="watch") = GLASSEYE The answer is GLASSEYE.

Quartz watch that doesn't look real? (5,3)

Guardian Cryptic #25599 | 6 Down | 2012-04-02 flower