Warned about treadle (7)
I believe the answer is:
alerted
'warned' is the definition.
(alerting is a kind of warning)
'about treadle' is the wordplay.
'about' is an anagram indicator.
'treadle' is an anagram of 'ALERTED'.
(Other definitions for alerted that I've seen before include "Warned, made aware" , "Related about warning notified" , "Given warning" , "Warned or aroused to a sense of danger" , "Altered, having been put on guard" .)