I've been toying over this for a while.
17a) Resentment of female boomer? (10) - I - T - R - E - S
I'm thinking Bitterness with 'ess' denoting female but can't find the link with Boomer = Bittern.
Checked in the Chambers and their is no ref to a boomer being a bird, the only creature link is a kind of Kangaroo.
Have you guys got any ideas. Cheers