Censor bleep keyboard shortcut
Pretty much no matter how loud you play it, the profanity will be audible to some extent. Plus, it's hard to predict when it's coming (which is why networks need to use 10-second delays when broadcasting live stuff). It's best to edit this in iMovie by detatching the audio and using the Split command before the offending word, then trimming the audio clip until the swear is out of your video. Then, drag your censor sound effect to the end of the first of your separated audio clips and trim that bleep to the start of the rest of your audio.

With this in mind, if the exact thing you requested in your question is what you want, you'll need to make a Service in Automator. First, open Automator, then create a Service in the next dialog. Find the Run Shell Script command and drag it into the drag-and-drop area. Copy-paste the text below into the text input area, replacing completePathOfFile with the path of your file:

Afplay completePathOfFile

Save this file and pick a memorable name.

Now go to System Preferences > Keyboard > Shortcuts > Services > Scroll to General. After finding the service you saved earlier, click the Add Shortcut button and type the F12 key. Hope this helps.