Pharma giant getting into development of magical pesticide, perhaps (12)

I believe the answer is:

agrochemical

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'pharma giant getting into development' is the definition.
I can't tell whether this definition defines the answer.

'magical pesticide perhaps' is the wordplay.
'magical' becomes 'agro' (I can't justify this - if you can you should give a lot more credence to this answer).
'pesticide perhaps' becomes 'chemical' (pesticide is a kind of chemical).
'agro'+'chemical'='AGROCHEMICAL'

'of' acts as a link.

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