This article is from the Crosswords FAQ, by James A. Lundon (jlundon@xstacy.enet.dec.com) with numerous contributions by others.
Of course, British and American clues will use different spellings. One
might use "hue" to clue "colour" and the other to clue "color". There
are less obvious differences though, because there is no absolute rule
about the fairness of a crossword clue. Americans tend to insist that
each word in the clue contribute to the definition or wordplay, while
British people may be less strict. For example, the following clue
once caused a few disagreements in this newsgroup:
"Could this replace a super tom?"
The answer (spelt backwards) is PARTESUOM. It's an anagram and the
whole clue is the definition: this type of clue is known as an "&lit"
clue. Some Americans complained that the words "Could this" were
superfluous as they didn't enter into the wordplay, while some British
people thought they added to the clue in an indefinable way. Another
example is that Americans don't like clues with only a single definition
and no subsidiary indication. For example, a Times (of London) clue:
"Kosher diet?"
The answer (backwards) is TESSENK. Although difficult to define, this
is acceptable because it's misleading and, once you've got the answer,
you can be sure you have it right.
It's impossible to define exactly what is acceptable, either to
Americans or to British people. You just have to learn from experience.
 
Continue to: