Malpractice on a coach to the capital of Egypt (5)
I believe the answer is:
abuse
'malpractice' is the definition.
(thesaurus)
'a coach to the capital of egypt' is the wordplay.
'coach' becomes 'bus' ('bus' can be a synonym of 'coach').
'to the capital of' suggests taking the first letters.
The first letter of 'egypt' is 'e'.
'a'+'bus'+'e'='ABUSE'
'on' is the link.
(Other definitions for abuse that I've seen before include "Vilify" , "Party official; dessert" , "Cruel treatment" , "Maltreat" , "Vituperation" .)