Why is it das Ringen?

Ringen is the verb ringen used as a noun, and verbs used as nouns are always neuter: das Ringen.

More verbs used as nouns
Sense 1
das

Meaning

[1] Sport: Martial arts that are practiced with grips

[1] Sport: Kampfsportart, die mit Griffen betrieben wird

[2] violent striving

[2] heftiges Streben

Examples

[1] Wrestling is a sport with a lot of physical contact.

[1] Ringen ist eine Sportart mit viel Körperkontakt.

[2] The struggle for self-control took away her last strength.

[2] Das Ringen um die Selbstbeherrschung nahm ihr die letzte Kraft.
More source examples (1)

These dictionary examples can include historical and less common uses.

[2] The struggle for a compromise goes into the second round.

[2] Das Ringen um einen Kompromiss geht in die zweite Runde.

Declension

1 Singular Plural
Nominativ das Ringen —
Genitiv des Ringens —
Dativ dem Ringen —
Akkusativ das Ringen —

Pronunciation

Dictionary entries include material from Wiktionary. Wiktionary