Cyclically just means that a clue can start anywhere in the row or column but will then continue normally until you reach the end of that row or column, and then you carry on from the top. Example:-
Imagine the 2 answers to 1a are HOTSPUR and CENTIPEDE - HOTSPUR might start anywhere along the first row, say, for example, the 4th square along - then you'd have
PEDEHOTSPURCENTI
You really need the normal 11a to get a foothold but, once you do, it does all fall neatly in to place.