The sentence "Her only regret is not dancing at the wedding." contains a gerund.
A gerund is an -ing verb that is used as a noun. In this sentence, "dancing" is the noun.
Daring Roger was the first to venture out onto the dance floor. (Daring is an adjective describing Roger)
Lucy is going to the party, as well. (Going is part of the verb phrase 'is going')
Dancing lessons are her first choice. (dancing is an adjective describing lessons)
