Small beer

Small beer was, judging by his what Henry Hawksworth's tombstone, the thing that caused his death. As Ben read to Polly, the tombstone said:
 * Henry Hawksworth, he did die
 * Of drinking too much small beer
 * When he was dry

The recitation jogged the First Doctor into a better understanding of the code the churchwarden had given as a sort of key to finding Avery's gold. It led the Doctor to look for Daniel Smallbeer's tomb. (TV: The Smugglers)

Behind the scenes
Small beer was a low-alcohol beer that was made in earlier centuries in order to, as the tomb inscription implied, serve the place that water would today. In earlier times, water was often not safe to drink, and the fermenting and brewing process would make water potable.