Biting article by plain-clothes officers (4)
I believe the answer is:
acid
'biting' is the definition.
(I've seen this before)
'article by plain-clothes officers' is the wordplay.
'article' becomes 'a' (the indefinite article in English).
'by plain clothes officers' becomes 'cid' (I am not sure about this - if you are sure you should believe this answer much more).
'a'+'cid'='ACID'
Can you help me to learn more?
(Other definitions for acid that I've seen before include "Vinegary" , "Sour-tasting" , "Type of chemical" , "bad rain" , "Sarcastic - tart" .)