Dragon! Dragon! Rock the Dragon!
Come, a-come get me!
Also while listening to the song, I did not feel like they say Come, a-come get me!
Is there any meaning existing or is it just for sound effects?
Listen to the song at 0:42 at Video.
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Yeah, I heard a come at 0:42. It's just a rhythmic filler sound. When you listen to sung language, you're gonna hear a lot of "extra syllables" thrown in because the artist is singing music, not prose. But sometimes it'll be due to dialect: See 'in-a my heart' correct, or only 'in my heart'?.
In contexts other than the one you ask about, a come could be part of a dialect other than standard English. That is what appears to be happening in the publication called
Dem a come
where dem is most likely a representation of the pronoun them (in subject position, where standard English would use they) and a could be a shortening of of or have, as it is in I'd a come. See If Ida Been Here, Ida Been There.
English does has the gerund form a-coming, whose usage can be traced to Old English. See a fighting for the glory - how do you understand this type of grammar? and the ELU links from that question.
It is possible that speakers who nowadays say I'm a-coming could say a-come and get me. That is not what is happening in the music you cite.