Clue: Unions associated with Attlee and Freud (not the Liberal)? (7)
Answer: CEMENTS
Explanation: Definition: Unions
 "Clements"(plural of "Clement", the first names of Attlee, former British PM, and Freud, British Liberal MP and broadcaster) **minus**(not the) "L"(abbrev. for "Liberal", a member of the Liberal Party).
Defn: I'm not sure about this. "cement" and "union" as nouns are not synonymous – the former achieves the latter; and unlike "cement", "union" cannot be a verb.