Peril transformed garden (6)
I believe the answer is:
danger
'peril' is the definition.
(I know that peril can be written as danger)
'transformed garden' is the wordplay.
'transformed' is an anagram indicator.
'garden' is an anagram of 'DANGER'.
(Other definitions for danger that I've seen before include "Ranged about in some peril" , "Peril, threat" , "Peril in garde" , "Peril, hazard" , "Peril, exposure to harm" .)