re: Poker & $200 NLHE Full Ring: $1/$3 Live - Getting check-raised on A789 turn
Villain flatting the flop reduces the chances he's made a set, but it could be there.
My guess before the checkraise is villain has something like 56s, 8c9c, 78s, 9c10c, KcXc. If villain has 78s or 89s and wants to avoid calling an overbet on the river he/she may check raise the turn hoping to get either a fold or freeze you on the River with another check raise threat. If you go over the top on the turn, he knows 78 and 89 are dead and avoids paying off a large river bet..... But considering your stack size, this is highly unlikely. So the villain either has a monster draw or the made straight.
The 56 straight is totally possible but has to be there over 1/2 of the time for your play to be a losing play. You risked $50 to win $66, then $176 to win $206. Because of your stack size, I'd say you made the right play.
If you both had like $400 behind and you make the same move, then that's a mistake. You should check.
Checking the turn isnt so bad either because you will have great odds
to call a decent river bet. You don't want to give the flush/straight draws free cards, but two pair is very likely here as well and as long as you avoid one of the 14 scare cards on the River, it's an easy call.