Force queen to wear hat (6)
I believe the answer is:
torque
'force' is the definition.
(force in physics)
'queen to wear hat' is the wordplay.
'queen' becomes 'qu' (abbreviation for queen).
'to wear' indicates putting letters inside (to wear something is to be covered up by it).
'hat' becomes 'tore' (I can't explain this - if you can you should believe this answer much more).
'qu' inserted within 'tore' is 'TORQUE'.
Can you help me to learn more?
(Other definitions for torque that I've seen before include "Rotating force" , "Rotational force; roquet (anag.)" , "Twisting force - twisted necklace" , "Necklace of twisted metal" , "Quoter (anag.)" .)