It's a tricky one to see. According to the wiki, "Once the drinks shop person appears, you can talk to them, one of the discussion paths ends with suggesting they move elsewhere, next time you load the area the shop has disappeared, leaving a path in the grass which circles up rightwards into the SBA area."
So, look closely around the big rock to the upper right of Pete the Painter's pink statue. There's a faint (to these old eyes, at least) twisting path that leads to the SBA. Hope this helps.