ADJ on n
The 'weak' and 'strong' group
These adjectives indicate a judgement about the extent of someone's knowledge or the way they convey it.
clued-up correct excellent good strong weak wrong
Whenever I've heard him talk I've always found him clued-up on whatever he was talking about.
Malcolm may have been weak on theory, but with his dress, his behavior, and even his art, he laid claim to being the big revolutionary on campus.