A solution may well be DISSECTED, with each element being dealt with separately - and bear in mind that an ‘element’ can be anything from a single letter to a complete word or phrase. At this stage you can only guess whether the solution to a clue is likely to be dissected into two or more elements; the length of the word is one hint (in this case, there are six letters; it says so in brackets at the end of the clue), and the length of the clue is another. In our example, the dissection is probably:

Accountant / 
    adds fifty-one / 
    and a hundred / 
    and arrives at nothing, / 
    materially

 There are several ways the compiler may clue each element. Remember, though, that although the compiler will have tried to make the clue tricky, and even to mislead you if possible, there are rules and compilers don’t like to cheat! Remember, too, that somewhere in the clue there should be a DEFINITION – in other words you have a cryptic clue, or a series of cryptic mini-clues dealing with individual elements, and you also have some sort of clue to the entire solution.