British troops accordingly keeping queen's men in order (8)
I believe the answer is:
brethren
'men in order' is the definition.
'brethren' can be an answer for 'order' (I've seen this before). I'm unsure of the 'men in' bit.
'british troops accordingly keeping queen's' is the wordplay.
'british troops' becomes 'bre' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'accordingly' becomes 'then' (I've seen this in another clue).
'keeping' is an insertion indicator.
'queen' becomes 'r' (abbreviation for regina, e.g. in ER ).
'then' placed around 'r' is 'thren'.
'bre'+'thren'='BRETHREN'
Can you help me to learn more?
(Other definitions for brethren that I've seen before include "Archaic brothers" , "Fellow males in an order" , "Old plural of brother" , "Fellow Christians or members of a religious order" , "like John and Charles Wesley, perhaps" .)