Become active, ultimately subsisting on fruit (2,4)

'become active' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'ultimately subsisting on fruit' is the wordplay.
'ultimately' suggests the final letters.
'on' means one lot of letters go next to another.
'fruit' becomes 'olive' (I've seen this before).
The last letter of 'subsisting' is 'g'.
'g'+'olive'='GO LIVE'

Can you help me to learn more?