Criminal clear about detective getting origin of root (7)
I believe the answer is:
radicle
'origin of root' is the definition.
(botanical term)
'criminal clear about detective' is the wordplay.
'criminal' is an anagram indicator.
'about' means one lot of letters goes inside another.
'detective' becomes 'di' (Detective Inspector abbreviation).
'clear' with letters rearranged gives 'racle'.
'racle' enclosing 'di' is 'RADICLE'.
'getting' acts as a link.
(Other definitions for radicle that I've seen before include "part of plant" , "bit of a nerve" , "A little root" .)