Answer:

purr

Answer	Crossword Clue
PURR	Kitty's satisfied sound
PURR	Good engine sound
PURR	Contented kitty sound

PURR	Sound content
PURR	Engine sound
PURR	Happy engine sound
PURR	Abyssinian "aah"
PURR	Happy hum
PURR	Sound of happiness
PURR	Sound of a well-tuned engine
PURR	Siamese sound

PURR	Smooth idle
PURR	Smooth-running sound
PURR	Sound of contentment
PURR	Contented murmur
PURR	Copy cats?
PURR	Cat nap sound
PURR	Contented cat's sound
PURR	Run smoothly

PURR	Contented sound
PURR	Be catty
PURR	Relaxed sound
PURR	Run really well
PURR	Run softly
PURR	Sound smooth
PURR	Contented kitten's sound
PURR	Manx murmur

PURR	Music to a cat lover's ears
PURR	Run well
PURR	Siamese sign of contentment
PURR	Sound finely tuned
PURR	Contented kitty's sound
PURR	Show contentedness, perhaps
PURR	Siamese sound of contentment
PURR	Sound from a Siamese

PURR	Sound from an Abyssinian
PURR	Sound of a fine-tuned engine
PURR	Feline hum
PURR	Happy cat's sound
PURR	Sound of pleasure