Medicine provided by clergyman about four (8)
I believe the answer is:
curative
'medicine' is the definition.
(curative is a kind of medicine)
'clergyman about four' is the wordplay.
'clergyman' becomes 'curate' (curate is a kind of clergyman**).
'about' means one lot of letters goes inside another.
'four' becomes 'iv' (roman numeral).
'curate' going around 'iv' is 'CURATIVE'.
'provided by' acts as a link.
(Other definitions for curative that I've seen before include "health-giving" , "Therapeutic" , "Healing" , "Restoring to health" , "Medicine" .)