Christmas card conceals a shout of pain from the master (4,6)
I believe the answer is:
noel coward
'the master' is the definition.
Both the definition and answer are singular nouns.
Perhaps you can see a link between them that I can't see?
'christmas card conceals a shout of pain' is the wordplay.
'christmas' becomes 'noel' (synonyms).
'conceals' is an insertion indicator.
'a shout of pain' becomes 'ow' ('ow' might be said when in pain).
'card' going around 'ow' is 'coward'.
'noel'+'coward'='NOEL COWARD'
'from' is the link.
Can you help me to learn more?
(Other definitions for noel coward that I've seen before include "He wrote" , "Old playwright" , "dramatist" .)