Private Eye doctored, so some people say (5)
I believe the answer is:
spade
'private eye' is the definition.
(fictional detective Sam Spade)
'doctored so some people say' is the wordplay.
'doctored' becomes 'spayed' (doctor can mean to neuter or spay).
'so some people say' indicates a 'sounds like' (homophone) clue.
'spayed' sounds like 'SPADE'.
(Other definitions for spade that I've seen before
include
"Garden implement"
,
"One in a suit"
,
"Garden tool and card suit"
,
"10