Deploy it thoroughly in a manner that is beneficial (8)
I believe the answer is:
usefully
'in a manner that is beneficial' is the definition.
Both the definition and answer are adverbs. Maybe you can see a link between them that I can't see?
'deploy it thoroughly' is the wordplay.
'deploy' becomes 'us' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'it' becomes 'e' ('e' can mean 'electronic' which is similar to 'IT').
'thoroughly' becomes 'fully' (I've seen this in another clue).
'us'+'e'+'fully'='USEFULLY'
Can you help me to learn more?
(Other definitions for usefully that I've seen before include "In a productive manner" , "in a way that's beneficial" , "in handy manner" , "in helpful manner" , "Advantageously" .)