Laminate used for worktops — police workers supply it (6,4)
I believe the answer is:
formic acid
'workers supply it' is the definition.
(worker ants might produce formic acid)
'laminate used for worktops police' is the wordplay.
'laminate used for worktops' becomes 'formica' (material used to make kitchen worktops etc).
'police' becomes 'CID' (abbreviation for Criminal Investigation Department).
'formica'+'cid'='FORMIC ACID'
(Other definitions for formic acid that I've seen before include "Substance emitted by some ants" , "Tannery chemical" .)