Technical detail briefly included in specialist trade union’s brochure (10)
I believe the answer is:
prospectus
'brochure' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for prospectus that I've seen before include "Booklet of what's on offer" , "Brochure giving details of college courses etc" , "University entering opportunities for success in brochure" , "Programme" , "Outline plan for approval" .)