Dime wasted by Catholic doctor (5)
I believe the answer is:
medic
'doctor' is the definition.
(doctor is a type of medic)
'dime wasted by catholic' is the wordplay.
'wasted' is an anagram indicator.
'by' means one lot of letters go next to another.
'catholic' becomes 'c' (abbreviation as in RC for Roman Catholic).
'dime' with letters rearranged gives 'medi'.
'medi'+'c'='MEDIC'
(Other definitions for medic that I've seen before include "Eg, doctor" , "What was Basutoland" , "Health worker" , "He may offer treatment" , "Physician (informal)" .)