Certain hormone is implicated in my mood (9)

I believe the answer is:

cortisone

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'certain hormone' is the definition.
'cortisone' can be an answer for 'hormone' (cortisone is a kind of hormone). I'm unsure of the 'certain' bit.

'is implicated in my mood' is the wordplay.
'implicated in' is an insertion indicator.
'my' becomes 'cor' (both are expressions of surprise).
'mood' becomes 'tone' (tone is a kind of mood).
'cor'+'tone'='cortone'
'is' inserted within 'cortone' is 'CORTISONE'.

Can you help me to learn more?

(Other definitions for cortisone that I've seen before include "hormone used in medicine!" , "Drug" , "Steroid" , "anti-inflammatory one" .)

I've seen this clue in The Times.

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