Examine Bill, initially lacking a certain hormone (12)

I believe the answer is:

testosterone

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

'examine bill initially lacking a' is the wordplay.
'examine' becomes 'test' (synonyms).
'bill' becomes 'poster' (synonyms).
'initially lacking' means to remove the first letter.
'a' becomes 'one'.
'poster' with its first letter taken away is 'oster'.
'test'+'oster'+'one'='TESTOSTERONE'

Can you help me to learn more?

(Other definitions for testosterone that I've seen before include "stimulator of particular sexuality" , "Male sex hormone" , "It might make a man of you" , "male driver?" .)

I've seen this clue in The Times.

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