Musketeer able to take a shot (5)

I believe the answer is:

athos

I'm a little stuck... Click here to teach me more about this clue!

'musketeer' is the definition.
(I've seen this in another clue)

'able to take a shot' is the wordplay.
'a shot' can be anagrammed to 'ATHOS'.
But, I am not clear how the anagram is indicated.

Can you help me to learn more?

(Other definitions for athos that I've seen before include "Literary musketeer" , "Mount - musketeer" , "Appropriating" , "Brave soldier" , "Greek monastic mountain" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app