Earth holds power to go bad (5)
I believe the answer is:
spoil
'go bad' is the definition.
(synonyms)
'earth holds power' is the wordplay.
'earth' becomes 'soil' (soil is a kind of earth).
'holds' means one lot of letters goes inside another.
'power' becomes 'p'.
'soil' enclosing 'p' is 'SPOIL'.
'to' acts as a link.
(Other definitions for spoil that I've seen before include "baby" , "Destroy or ruin" , "Having dredged-up material" , "Booty" , "Diminish or destroy the value or quality" .)