Didn't tie up as much when full of such energy (9)
I believe the answer is:
boundless
'didn't tie up as much when full' is the definition.
I can't judge whether this defines the answer.
'of such energy' is the wordplay.
I cannot really see how this works, but
'of' could be 'o' and 'o' is located in the answer.
'energy' could be 'e' (physics symbol as in E=mc2) and 'e' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for boundless that I've seen before include "Having no limit, extensive" , "Seemingly without limit" , "Unlimited" , "Without limits" .)