Reset rye rolls, plus sides of anchovy paste (10)
I believe the answer is:
yesteryear
'sides of anchovy paste' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'reset rye rolls plus' is the wordplay.
I cannot really understand how this works, but
an anagram of 'reset' is 'ester' which is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for yesteryear that I've seen before include "nostalgic time, perhaps" , "Twelve months ago" , "Time disappeared" , "Days gone by" , "The recent past" .)