"Theme word carrying egg on two wheels" (7)
"Swedish chemist with an equation arrived before one with us" (9)
"A lot know the financial times can be the source of idle gossip" (4, 2, 3, 4)
The theme word is bird
Thanks a lot
15a Scooter - 'scoter' (bird [theme], carrying) 'o' (egg)
19a Arrhenius - 'arr(ived) i (one) us' + 'hen' (theme)
21a Talk of the town - anag 'a lot know the FT'