Peril in untidy garden (6)
I believe the answer is:
danger
'peril' is the definition.
(I know that peril can be written as danger)
'untidy garden' is the wordplay.
'untidy' is an anagram indicator.
'garden' anagrammed gives 'DANGER'.
'in' is the link.
(Other definitions for danger that I've seen before include "Garden (anag) - peril" , "'Peril, risk (6)'" , "Undesirable possibility" , "Peril, jeopardy" , "Peril, threat" .)