1) Able to see right through 2) Able to see through 3) Aboard 4) Advance towards 5) Appended 6) Atop 7) Atop of 8) Aware 9) Aware of 10) Aware of a hoax 11) Aware of a scam 12) Aware of a scheme 13) Aware of skulduggery 14) Aware of the real nature of 15) Aware of trickery 16) Aware of, slang 17) Catch or latch follower Found on https://www.crosswordclues.com/clue/onto
On'to preposition [ On + to . Confer Into .] On the top of; upon; on. See On to , under On , preposition Found on http://www.encyclo.co.uk/webster/O/21