Defending anything in a dream is protecting it spiritually, perhaps from contamination or from penetration. Defending any type of sacred space would have this meaning.
Psychological / emotional perspective: Defending our position suggests that there is a conflict of some sort in us, maybe of ideas or principles.
Material aspects: Putting up a defence, perhaps a wall or barrier, signifies that we feel threatened in some way. We may have to justify our position over a situation in our waking lives.
Gives gender - specific: If a woman is defending herself in a dream she is guarding against some kind of ‘assault’, often of her own private space.
If a man has such a dream, it shows he will defend against his own vulnerability.