Checking for a string in a list

I'm building a 'scrabble' game in Python. Basically, the user is given 7 randomly generated letters and these are stored in the list randomLetters. They then enter a word using those letters - this is a string stored as Player1Word

The bit I am stuck on is where I need to validate that the user has entered a valid word - e.g is Player1Word only using letters from randomLetters

I have looked around Stack Overflow but cannot seem to find a solution that works.