You can't answer a question well unless you understand what it means. Working out what a question means, however, is more complicated than you might think, because any essay question you get at university is really an invitation to consider the intellectual context or field in relation to which the question is an interesting one.
At the most basic level, you need to understand what is implied by the words used in the question, and here looking up words you feel unsure about in a good dictionary might be useful - although simply copying out a definition in your essay won't help. You need to beware of words such as "ideology" or "culture", which most people think they understand, but in academic contexts have some very complicated debates surrounding them. When we ask somebody what they mean, however, we are normally asking what the intention is behind what they've said rather than for dictionary definitions. Defining the problem is about understanding why a tutor has set a particular question, ie the expectations the tutor attaches to it.
A good way of arriving at an understanding of a question is to break it down into key issues - the real intention behind a question will often be to get you to explore the relationship between two or three of these. A key issue is significant only because it relates to a field, or larger intellectual context, so it is worth asking yourself what this is (typically this will be a subject area covered in the module).