Removing trousers the Queen is making use of (10)
I believe the answer is:
exercising
'making use of' is the definition.
(exercising is a kind of making use of)
'removing trousers the queen' is the wordplay.
'removing' becomes 'excising' (to excise is to cut out or remove).
'trousers' is an insertion indicator (trouser can mean to steal or take).
'the queen' becomes 'ER' (Elizabeth Regina).
'excising' enclosing 'er' is 'EXERCISING'.
'is' acts as a link.
(Other definitions for exercising that I've seen before include "activity in gym?" , "training" .)