If this problem always occurs for a particular song, you may want to re-load it from your iTunes library. First, listen to the same song in iTunes (on the computer) to confirm it does not happen there.
If the problem occurs randomly with any song, you may want to do a Restore using iTunes; the cause may be data corruption on the iPod's storage. The Restore button is on the iPod's Summary settings screen in iTunes. This will erase the iPod, reinstall its software, and set it to default settings.
Use iTunes to restore your iPhone, iPad, or iPod to factory settings - Apple Support
Then, sync your songs back to iPod as desired.