A gerund is a present participle (-ing verb) used as a noun. If the ‑ing verb acts as an adjective, it is not a gerund but a participial adjective. Thus, the expression a winning hand is not a gerund. It is simply a present participle (winning) used as an adjective.
A gerund may serve virtually any noun function. For example, it can act as the subject of a sentence, as a direct object, or as the object of a preposition. Examples of each follow:
Winning the race became his obsession. (Gerundive phrase serving as the grammatical subject.)
I like swimming. (Gerund serving as the direct object of the verb like.)
He perfected his technique of swinging the golf club. (Gerundive phrase serving as the object of the preposition of.)