Final answer:
The best context clue for the meaning of 'substance' in the passage is the word 'waste,' which suggests that 'substance' refers to money or assets that are being spent recklessly during a wedding.
Step-by-step explanation:
The passage suggests that the parents of the bride and bridegroom often face financial troubles because of expenses associated with marriage. The word that provides the best context clue for the meaning of the word substance is waste, which implies that money and possibly other assets are being spent or consumed recklessly. Other context clues from the passage, such as references to bringing themselves to ruin and wasting their time, support the interpretation that substance refers to financial resources or wealth.