There is a way to do it, however it can be a bit complicated and requires a unix web host with php 5, so be warned.
Step 1
The first thing you have to do is add the maker channel. You do this the same way you'd add any other channel, by clicking "channels" at the top of the page and searching for it, then clicking on it and pressing the "add channel" button.
Step 2
Create a blank php document on your webhost. It doesn't really matter where, as long as you can access it with a browser.
Step 3
What you do now, is make a recipe where your trigger activates the maker channel. Once you get your trigger set up, just click the maker channel then "Make a web request". Then type in the web URL of the document we made in step 2 in the URL field. Change the method to GET and leave the other fields blank.
Step 4
Now make a recipe that's triggered by a web request. Make the event name whatever you want, as long as you remember it. Make the "that" of the recipe whatever you want it to do.
Step 5
Now, we add code into that PHP document we made back in step 2. Add this code in, changing time time allowed (currently 6am), the pass, the time zone, and the URL where you'll change "example-key" to your key (found here)and {{event}} to the event you named in step 4.
<?php
date_default_timezone_set("EST");
$time = strftime("%H");
if($time == 6){
echo exec('curl -X POST https://maker.ifttt.com/trigger/{{event}}/with/key/example-key');
}
}
?>
Save the document, and you're done.