Last few. 1 across First, clear, carrying old rider imposingly? (7) GES????
4D. Muscovite maybe again exploits energy being twicw cut (4) ?U??
7D Former reduction, one introduced in food (8) ALA??ENT. Thanks!
4d is REUSES (again exploits) with E (energy) being removed twice.
I think you have 1d wrong, the first letter in 1a is a B. The wordplay in 1d consists of a word meaning a heavy blow (or a party!) followed by the standard crossword abbreviation for nothing.
Thank you - I thought 1d was 'gusto', but I know the answer you are cluing and have amended the grid accordingly. I now have completed the crossword (I think!) and thank you for your assistance.