Slow to catch on Crossword Clue

 The answer to the crossword clue "slow to catch on" can be DULL, OBTUSE, or LURKY. These words all mean someone who is slow to understand or learn new things.

Here are some other possible answers for the crossword clue "slow to catch on":

DENSE

INERTIAL

UNSOPHISTICATED

RETARDED

SENILE

The specific answer that you are looking for may depend on the context of the crossword puzzle. For example, if the clue is specifically looking for someone who is slow to understand new ideas, then the answer would be DULL. However, if the clue is more general and is simply looking for someone who is slow to learn new things, then the answer could be any of the words listed above.

I hope this helps! Let me know if you have other questions or requests.