Unknown deli junked produce (5)
I believe the answer is:
yield
'produce' is the definition.
(I know that yield is a kind of produce)
'unknown deli junked' is the wordplay.
I cannot quite see how this works, but
'unknown' could be 'y' (algebra) and 'y' is located in the answer.
an anagram of 'deli' is 'ield' which is within the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for yield that I've seen before include "return on capital" , "amount of energy from 14 [EXPLOSION]" , "earnings" , "Produce, generate" , "Supply" .)