America wasting energy in this way (4)
I believe the answer is:
thus
'in this way' is the definition.
(synonyms)
'america wasting energy' is the wordplay.
'america' becomes 'theus' (I've seen this in another clue).
'wasting' is a deletion indicator.
'energy' becomes 'e' (physics symbol as in E=mc2).
'theus' with 'e' taken out is 'THUS'.
(Other definitions for thus that I've seen before include "Therefore, hence" , "In this way" , "as indicated" , "'So, therefore (4)'" , "In this manner" .)