Renewable energy from a farm perhaps is used by flighty types as part of a campaign (3,5)
I believe the answer is:
air power
'a farm perhaps is used by flighty types as part of a campaign' is the definition.
I can't judge whether this definition defines the answer.
'renewable energy' is the wordplay.
'renewable' becomes 'air' (I can't explain this - if you can you should give a lot more credence to this answer).
'energy' becomes 'power' ('power' can be a synonym of 'energy').
'air'+'power'='AIR POWER'
'from' is the link.
Can you help me to learn more?
(Other definitions for air power that I've seen before include "might get this from a wind farm?" , "Military" , "Flying strength" .)