In the Anglo-Saxon poem, "The Wanderer," "gold-lord" is a kenning that describes what the Wanderer is searching and hoping for.
A kenning is a compressed metaphor that is an attempt by the poet to go beyond a limited vocabulary. A kenning is a metaphorical attempt at naming.
In this case, a gold-lord is a man with a mead hall. The mead hall was the center of Anglo-Saxon life. It was the center of the community, the village, so to speak. But life in Anglo-Saxon England was precarious. No central government, police force, or formal system of law existed, so life was unstable. If your mead hall was attacked and overtaken by another mead hall's inhabitants, you were either killed or exiled. This is what the Wanderer has suffered, and why he is looking for a new mead hall, a new "gold-lord."
Specifically, gold-lord is simply lord of the gold. Such a man is the leader of the mead-hall, the provider and protector. And the mead hall provides companionship and stability, friends one can figuratively open up to and communicate with. Without a mead hall, the Wanderer keeps to himself and does not share information, feelings, etc., with others.
The poem mourns the wanderer's lost clan. This is not just a political loss, but, in a personal loss as well. With the loss of his mead hall and his fellow warriors, the wanderer is truly alone. As he says,
There is none now living
to whom I dare
of my innermost thoughts.
In my translation of the poem, the "gold-lord" kenning is translated as "gold-friend," and I think that version captures a little of what the wanderer has lost. The interesting thing about kennings as poetic forms is how much meaning they can contain in just two words; here, "gold-lord" can mean "lord of the gold" or "a golden (e.g., excellent) lord"; or, to consider the alternate translation, a "friend of gold" or the friend who gives out gold; these ideas are conflated in the kenning, because the idea of treasure, and reward, and friendship, are all linked in the Anglo-Saxon tradition. As the poet puts it,
He who has tried it knows
how cruel is
sorrow as a companion
to the one who has few
the path of exile (wræclast) holds him,
not at all twisted gold,
a frozen spirit,
not the bounty of the earth.
He remembers hall-warriors
and the giving of treasure
How in youth his lord (gold-friend)
to the feasting.
All the joy has died!