Cycling Morecambe Pier, a penny for one case of Vietnamese spring rolls (4,5)
I believe the answer is:
rice paper
'case of vietnamese spring rolls' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'cycling morecambe pier a penny for one' is the wordplay.
I cannot really understand how this works, but
'a' could be 'per' (eg 'one a day' means 'one per day') and 'per' is found in the answer.
'penny' could be 'p' (short for pence) and 'p' is found within the answer.
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for rice paper that I've seen before include "thin basis for dish" , "baking aid" , "Thin edible base for baking" , "Thin edible sheet used in cooking" , "Cook it and eat it, don't write on it" .)