A returned high ball is hard to stop (7)
I believe the answer is:
abolish
'stop' is the definition.
(to abolish is to stop or ban)
'a returned high ball is hard' is the wordplay.
'returned' says the letters should be written in reverse.
'high ball' becomes 'lob' (I've seen this before).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'lob' written backwards gives 'bol'.
'a'+'bol'+'is'+'h'='ABOLISH'
'to' is the link.
(Other definitions for abolish that I've seen before include "Cancel or abrogate" , "Put an end to (something)" , "Put an end to, a rule perhaps" , "Put an end to (practice)" , "Get rid of" .)