Flogged one Queen's Guardsman? (7)
I believe the answer is:
soldier
'guardsman?' is the definition.
(guardsman is a kind of soldier)
'flogged one queen's' is the wordplay.
'flogged' becomes 'sold' (I've seen this before).
'one' becomes 'i' (Roman numeral).
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'sold'+'i'+'er'='SOLDIER'
(Other definitions for soldier that I've seen before include "trained killer" , "Army fighter" , "piece of bread" , "Eg, private" , "Warrior" .)