Clavado literally means "nailed" or "stuck". While it can refer to something physically embedded, in this context, it's used metaphorically to describe being emotionally stuck or fixated on someone.
The singer uses it to express that he is still deeply hung up on his ex, singing, "Que solamente yo sigo clavado" (That only I remain stuck/fixated). It's a vivid and relatable way to describe the lingering feelings after a breakup.
This song is basically one long, honest “I still love you” message that slipped out four months after the breakup. The singer knows they were supposed to stay just friends, but the feelings clearly did not get that memo. From the first line, “Ya van cuatro meses desde que cortamos” [It’s been four months since we broke up], you can feel how they’ve been counting the time. They imagine the ex is probably fine “del otro lado” [on the other side], moving on with life, while they’re the one still stuck. That contrast is the whole tension of the song: one person healing, the other still completely hooked.
Over and over, the singer keeps answering an invisible question: “Por si te lo preguntas” [In case you’re wondering]. Every time, the answer is the same and a little more intense. “Hoy solamente quiero estar contigo” [Today I only want to be with you], “Te extraño mucho” [I miss you a lot], “No ha pasado ni siquiera un día que yo no piense en ti” [Not a single day has gone by that I don’t think of you]. They even admit they don’t know how to forget, “Aunque a Dios se lo pida” [Even if I ask God for it], which is both dramatic and very relatable. And the strongest line is almost over the top in its honesty: “Esta vida sigue siendo solamente tuya” [This life is still only yours]. It’s that kind of song you put on when you’re not over someone at all, and you’re half embarrassed, half proud of how ridiculously in love you still are.