There are several schemes how you could get this topology to work:

1. A=AP, B=Repeater (or bridge), C=Client
A = wireless network set up in AP or master mode, extension of wired network
B = wireless network will be range-extended (STA mode for connection to A, AP or master mode for connection to B), wired network is part of it
C = wireless network set up in STA mode connecting to B, wired network is part of it.

Disadvantages: Bandwidth might be reduced by as much as 50%. Hidden node problems may occur frequently. Range of B's antenna beam width must cover both A and B.

2. A=Client, B=AP, C=Client
A = wireless network in STA mode, connects wired network with B and C
B = wireless network in AP or "master" mode, wired network part of it
C = wireless network in STA mode, connects wired network with A and B

Disadvantages: Hidden node problems may occur frequently. Range of B's antenna beam width must cover both A and B.

Best solution: use 4 CPEs A wireless link to B wired to C wireless link to D.
Advantages: full bandwidth can be reached, no hidden node problems anymore, antennas can be precisely aligned.