@kikashi - it seems you have two problems:
1. mixed lighting (flash is cool compared to incandescent)
2. white balance is off.
I realize you only asked about #2, but in case you are amenable to help with #1:
If possible, put an incandescent gel over your flash when shooting (so flash light temperature matches room light temperature).
If not possible or too late now, then you may be able to compensate using Lr's locals which include temperature and tint now - a radial gradient may suffice or whatever works...
My apology in advance for answering a different question than you asked