A letter in the hospital pharmacy (5)

I believe the answer is:

alpha

'a letter' is the definition.
(alpha is a kind of letter)

'in the hospital pharmacy' is the wordplay.
'in' says the answer is hidden in the clue.
'ALPHA' can be found hidden inside 'the hospital pharmacy'.

(Other definitions for alpha that I've seen before include "European character" , "Foremost" , "star of utmost brilliance" , "Dominant" , "best score" .)

I've seen this clue in the Evening Standard.

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