Strangely brusque about using force (12)
I believe the answer is:
surprisingly
'strangely' is the definition.
'brusque about using force' is the wordplay.
'brusque' becomes 'surly' (I am not sure about this - if you are sure you should believe this answer much more).
'about' means one lot of letters goes inside another.
'using force' becomes 'prising' (as in prising something open).
'surly' going around 'prising' is 'SURPRISINGLY'.
Can you help me to learn more?
(Other definitions for surprisingly that I've seen before include "Amazingly" , "Unexpectedly" .)