Happy hormone in store and on order (9)
I believe the answer is:
serotonin
'happy hormone' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'in store and on order' is the wordplay.
'and' is a charade indicator (letters next to each other).
'order' indicates an anagram.
'in'+'store'='instore'
'instore' after 'on' is 'oninstore'.
'oninstore' anagrammed gives 'SEROTONIN'.
Can you help me to learn more?
(Other definitions for serotonin that I've seen before include "Chemical compound in body" , "Neurotransmitter hormone, involved in depression say" , "Compound in brain" , "Compound in the blood affecting sleep and depression - soon inert (anag)" , "Neurotransmitter compound; soon inert (anag.)" .)