Missionary imposing penalty for beheading (9)
I believe the answer is:
augustine
'missionary' is the definition.
(I've seen this before)
'imposing penalty for beheading' is the wordplay.
I cannot really understand how this works, but
'imposing' could be 'august' (I've seen this before) and 'august' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for augustine that I've seen before include "First Archbishop of Canterbury" , "Missionary" , "Friar" , "Saint" .)