Soldier punishing clan and monarch (6)
I believe the answer is:
lancer
'soldier' is the definition.
(I know that lancer is a type of soldier)
'punishing clan and monarch' is the wordplay.
I cannot really understand how this works, but
an anagram of 'clan' is 'lanc' which is within the answer.
'monarch' could be 'er' (abbreviation for Elizabeth Regina, British Queen) and 'er' is found in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for lancer that I've seen before include "Former cavalryman" , "Cavalry soldier" , "Spearman (as in dance?)" .)