Herb's top spin split the top of the wicket (5)
I believe the answer is:
basil
'herb's' is the definition.
(basil is a herb)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for basil that I've seen before include "Aromatic herb in pesto" , "Sweet-smelling herb" , "Fragrant herb" , "Boy - herb" , "A herb; Cardinal --- Hume" .)