Turn up with a growl, yet seem pleased (4)
I believe the answer is:
purr
'seem pleased' is the definition.
I can't judge whether this defines the answer.
'turn up with a growl' is the wordplay.
'turn' is a reversal indicator.
'with' says to put letters next to each other.
'a growl' becomes 'rr' (I can't justify this - if you can you should give a lot more credence to this answer).
'up' written backwards gives 'pu'.
'pu'+'rr'='PURR'
'yet' is the link.
Can you help me to learn more?
(Other definitions for purr that I've seen before include "Cat's contented sound" , "Satisfaction from queen" , "Sound like happy cat" , "Cat's coo" , "Happy feline sound" .)