Reacting to a new wave the Queen's introduced (9)
I believe the answer is:
Here is my best explanation:
'reacting to' is the definition.
'a new wave the queen's introduced' is the subsidiary indication.
'a new' becomes 'an' (I've seen this in other clues).
'wave' becomes 'swing' (**).
'the queen' becomes 'er' (Elizabeth Regina).
'introduced' is an insertion indicator.
'swing' enclosing 'er' is 'swering'.
(Other definitions for answering that I've seen before include "Picking up receiver", "Replying", "Responding", "Acknowledging" and "responding".)