Ignorant, as police may be about how investigation ends (10)
I believe the answer is:
uninformed
'ignorant' is the definition.
(I know that ignorant can be written as uninformed)
'police may be about how investigation ends' is the wordplay.
'police may' becomes 'unformed' (I can't justify this - if you can you should believe this answer much more).
'be about' means one lot of letters goes inside another.
'how' indicates an anagram (I've seen this in other clues).
'ends' suggests removing the centre.
'investigation' with its middle removed is 'in'.
'in' anagrammed gives 'ni'.
'unformed' placed around 'ni' is 'UNINFORMED'.
'as' is the link.
Can you help me to learn more?
(Other definitions for uninformed that I've seen before include "Not knowledgeable" , "in the dark" , "Lacking intelligence" , "Missing dope" .)