A potential buyer - American - has the brochure (10)
I believe the answer is:
prospectus
'the brochure' is the definition.
(I've seen this before)
'a potential buyer american' is the wordplay.
'a potential buyer' becomes 'prospect' (I've seen this in another clue).
'american' becomes 'US' (United States).
'prospect'+'us'='PROSPECTUS'
'has' acts as a link.
(Other definitions for prospectus that I've seen before include "Programme" , "University entering opportunities for success in brochure" , "Advertising booklet for school or university" , "Outline plan for approval" , "Brochure giving details of college courses etc" .)