A novel musketeer (or a Tommy?) (5)
I believe the answer is:
athos
'a novel musketeer' is the definition.
'athos' can be an answer for 'musketeer' (I've seen this before). I'm unsure of the 'a novel' bit.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for athos that I've seen before include "Mount - musketeer" , "Colleague of Porthos, Aramis" , "Appropriating" , "Greek monastic mountain" , "Greek mountain; one of the three musketeers" .)