This is an irregular verb. It follows the conjugation pattern of the verb entender.
PresentPresente
El gato se defiende con sus garras.
The cat defends itself with its claws.
PreteritePretérito indefinido
Ella se defendió muy bien en el debate.
She defended herself very well in the debate.
FutureFuturo
Nos defenderemos juntos si hay problemas.
We will defend ourselves together if there are problems.
Imperfect SubjunctiveImperfecto de subjuntivo
Quería que mi hermano se defendiera solo en la escuela.
I wanted my brother to defend himself at school.