Green’s Dictionary of Slang

(Irish) common sense, awareness; determination.

1990		R. Doyle Snapper 64: They’ve more cop-on these days. Would you get married if you were tha’ age again these days?
2002		O’Byrne Files: Dublin Sl. Dict. 🌐 Cop-on, n., v. Common sense, understanding, streetwise knowledge.
2017		L. McInerney Blood Miracles 35: ‘Do you know how much energy I wasted gathering the cop on not to go looking for you to bring you home?’.