Possible Clues:

• Half a boilermaker ... and what's aptly hidden in 18-, 24-, 40- and 51-Across
• Whiskey follower, at times
• Shot follower, often ... and a hint to the starts of 17-, 23-, 39- and 48-Across
• Brew after a shot (and, in a way, what the end of 17-, 25-, 37-, or 51-Across can be)