One showing Mary pastry case from trattoria (5)
I believe the answer is:
pieta
'one showing mary' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'pastry case from trattoria' is the wordplay.
'pastry' becomes 'pie' (pie is a kind of pastry).
'case from' suggests removing the centre (the case or outside of the word).
'trattoria' with its centre removed is 'ta'.
'pie'+'ta'='PIETA'
Can you help me to learn more?
(Other definitions for pieta that I've seen before include "Devotional painting" , "Status of Virgin with body of Christ" , "Religious figures" , "religious picture?" , "Sculpture of Mary with Christ's body" .)