A spell of bowling is finished (4)
I believe the answer is:
over
'is finished' is the definition.
(over can mean finished or ended)
'a spell of bowling' is the wordplay.
I cannot quite see how this works, but
'of' could be 'o' and 'o' is located in the answer.
The remaining letters 'ver' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for over that I've seen before include "See 23" , "Six balls, as a unit" , "Finished like cricket period" , "Invalidate - upset" , "See 19" .)