The answers to the 12 special clues are all words which have different meanings in English and in Czech. One
meaning in each language is given by the clues. The superfluous letters spell out CZECH WORDS WWW DOT SLOVNIK DOT CZ USEFUL.
Slovník is the Czech word for dictionary and the site referred to is an online English/Czech and Czech/English dictionary.
I guessed that this puzzle would be unsuitable for a puzzle such as the Listener even though I was rather pleased
with some of the clues – non-Czech speaking solvers will have to rely entirely on the cited Internet link and the subject
is probably too obscure even for the Listener. I hope you enjoyed solving it.