Clue: Bill's outing in street through evergreen Berkshire town (5,7)
Answer: FIRST READING
Explanation: Definition: Bill's outing
 ST(abbrev. for "street") **contained in**(through) [ FIR(an evergreen coniferous tree) + READING(a town in Berkshire) ].
Defn: …, ie. the first presentation to parliament for discussion of a draft of a proposed law.