What does the cryptic crossword clue "Spot girl in the afternoon, signalling (3,4)" mean?

The wordplay uses a charade (building blocks). PIP (synonym="spot") + EMMA (synonym="EMMA") = PIPEMMA The answer is PIPEMMA.

Spot girl in the afternoon, signalling (3,4)

Guardian Cryptic #29210 | 17 Down | 2023-10-25 flower