What does the cryptic crossword clue "Film with violent evildoer / hero uncovered (7)" mean?

The definition is "Film". The wordplay uses a charade (building blocks). SLASH (synonym="SLASH") + ER (synonym="ER") = SLASHER The answer is SLASHER.

Film with violent evildoer / hero uncovered (7)

Times Cryptic #29110 | 20 Across | 2024-12-26 flower