1. cut the tip off.   Hint First letter clue   2. remove unwanted stuff; purify or cleanse.   First letter clue   3. interject or insert between.   First letter clue   4. melt ores for extraction of metal.   First letter clue   5. make invalid or weaken.   First letter clue   6. isolate to prevent spread of infection.   First letter clue   7. introduce into a larger body or unite.   First letter clue