Complex sentence: Tresham had no money to spare, his father's debts having reduced his inheritance, although he paid a small sum to Thomas Wintour, on the understanding that the latter was to travel to the Low Countries.
Split into simpler sentences: Tresham had no money to spare, his father's debts having reduced his inheritance. Tresham did, however, pay a small sum to Thomas Wintour on the understanding that he was travelling to the Low Countries.