Pesky green fly's last go (6)

I believe the answer is:

energy

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'pesky green fly's last go' is the definition.
I can't judge whether this definition defines the answer.

'green fly's last go' is the wordplay.
'last' suggests the final letters.
'go' indicates an anagram (I've seen 'went' mean this ('go' can mean move)).
The last letter of 'fly' is 'y'.
'green'+'y'='greeny'
'greeny' anagrammed gives 'ENERGY'.

Can you help me to learn more?

(Other definitions for energy that I've seen before include "Vigour, vim, vitality" , "'Vigour, vitality (6)'" , "Power; capacity for work" , "life" , "Go, zip" .)

I've seen this clue in the Sydney Morning Herald.

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