Hagen said quickly and proudly, "I was as good a son to him as you or
Mike, maybe better. I’m giving you a professional opinion. Personally
I want to kill all those bastards." The emotion in his voice shamed
Sonny, who said, "Oh, Christ, Tom, I didn’t mean it that way." But he
had, really. Blood was blood and nothing else was its equal.
Sonny brooded for a moment as the others waited in embarrassed silence.
then he sighed and spoke quietly. "OK, we’ll sit tight until the old
man can give us the lead.
(from The Godfather, by Puzo)
What is the meaning of we’ll sit tight here?
- Remain firmly in one’s place:
1.1. Refrain from taking action or changing one’s mind:
Have you tried to consult a dictionary? See the ODO for the above. Here, the meaning is figurative because the person in your question might not be sitting tight physically, so 1.1 is the best definition.
To rewrite your quote:
"OK, we will NOT take any action until the old man can give us the lead.