Answer: mydog

AnswerCrossword Clue
MYDOG

Me's partner, in a 1936 song

MYDOG

"... has fleas" (uke-tuning phrase)

MYDOG

It "has fleas" in an old ditty

MYDOG
"... has fleas" (instrument tuning line)
MYDOG
"..... Skip" (2000)
MYDOG" ..... has fleas"