Hiding expression of pain, crying — turning somewhat pale? (9)
I believe the answer is:
yellowing
'turning somewhat pale?' is the definition.
I can't judge whether this definition defines the answer.
'hiding expression of pain crying' is the wordplay.
'hiding' means one lot of letters goes inside another.
'expression of pain' becomes 'ow'.
'crying' becomes 'yelling' ('yell' can be a synonym of 'cry').
'ow' put into 'yelling' is 'YELLOWING'.
Can you help me to learn more?
(Another definition for yellowing that I've seen is " showing effects of age".)