Rash devil dials mistakenly (3-7)
I believe the answer is:
ill-advised
'rash' is the definition.
(synonyms)
'devil dials mistakenly' is the wordplay.
'mistakenly' indicates anagramming the letters.
'devil'+'dials'='devildials'
'devildials' with letters rearranged gives 'ILL-ADVISED'.
(Other definitions for ill-advised that I've seen before include "Rash" , "Not prudent" , "Unwise" , "Imprudent" .)