As a Musketeer, he can take a shot (5)
I believe the answer is:
athos
'as a musketeer he can take a' is the definition.
The definition suggests a singular noun which matches the answer.
'shot' is the wordplay.
I cannot quite see how this works, but
an anagram of 'shot' is 'thos' which is present in the answer.
A single letter 'a' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for athos that I've seen before include "Literary musketeer" , "Greek mountain; one of the three musketeers" , "Mount - musketeer" , "Comrade of Porthos and Aramis" , "Brave soldier" .)