Select part to form into a hard mass with delicacy (5-4)
I believe the answer is:
cream-cake
'select part to form into a hard' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'mass with delicacy' is the wordplay.
'mass' becomes 'cake'.
'with' means one lot of letters go next to another.
'delicacy' becomes 'cream' (I am not sure about this - if you are sure you should believe this answer much more).
'cake' put after 'cream' is 'CREAM-CAKE'.
Can you help me to learn more?
(Other definitions for cream-cake that I've seen before include "Sweet high-calorie food" , "Eg, an eclair" .)