I answered my first question today. A message popped up with guidelines. "Avoid asking for help, clarification, or responding to other answers." Really?? Seems draconian to me, unless i miss something. What if the answer isn't clear?
The idea of this automatic message is that answers should be good, relatively self-contained, objective responses to a question. When the guidelines suggest avoiding asking for clarification or responding to other answers, they don't mean to avoid asking for clarification at all costs. Instead, they mean don't ask for clarification in your answer.
There is a comment system for asking for clarification, responding to answers, etc. In fact, in the faq it is mentioned that comments should and will be used for clarification, for example.
But this might be very confusing, because there is a reputation limit to be able to comment on questions that aren't your own. You need 50 reputation, so you're almost there.
So to end, one can ask for clarification on answers, but this should be done in comments as opposed to other answers.