Davis changed to alternative counsel (7)
I believe the answer is:
advisor
'counsel' is the definition.
(I know that counsel can be written as advisor)
'davis changed to alternative' is the wordplay.
'changed' indicates an anagram.
'to alternative' becomes 'or'.
'davis' is an anagram of 'advis'.
'advis'+'or'='ADVISOR'
(Other definitions for advisor that I've seen before include "Assistant" , "One recommends" , "One offers recommendations" , "consultant" , "Mentor, counsel" .)