What holds the key to food production (5)
I believe the answer is:
wheat
'food production' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'what holds the key' is the wordplay.
'holds' is an insertion indicator.
'the key' becomes 'E' (a musical key).
'what' enclosing 'e' is 'WHEAT'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for wheat that I've seen before include "staple food" , "Grass whose grain is used to make flour" , "Cereal crop" , "Cereal for bread/pasta" , "food plant" .)