Industrious worker with plainclothes officers detaining a settler? (7)
I believe the answer is:
antacid
'settler?' is the definition.
(medicine that settles stomach acidity levels)
'industrious worker with plainclothes officers detaining a' is the wordplay.
'industrious worker' becomes 'an't' (ants are hard workers).
'with' says to put letters next to each other.
'plainclothes officers' becomes 'CID' (CID detectives don't wear a uniform).
'detaining' means one lot of letters goes inside another.
'ant'+'cid'='antcid'
'antcid' enclosing 'a' is 'ANTACID'.
(Other definitions for antacid that I've seen before include "Indigestion remedy" , "Medicine to settle the stomach" , "heartburn remedy" , "Substance used to treat stomach upsert" , "Stomach drug" .)