Crossword Puzzle Observed secretly

Clue: Observed secretly

Secretly watch, with "on" (SPY with 3 letters)
Helps secretly (ISINCAHOOTSWITH with 15 letters)
Place secretly (PLANT with 5 letters)
Secretly tie the knot (ELOPE with 5 letters)
Put a mike on, secretly (WIRE with 4 letters)
Secretly forms a team? (ELOPES with 6 letters)
When Purim is observed (ADAR with 4 letters)
Observed rigorously (STOODON with 7 letters)
Observed visiting (SEENAT with 6 letters)
Self-taught baseball great (who had secretly planned to get...) (SATCHELPAIGE with 12 letters)