Understood to have accumulated (8)
I believe the answer is:
gathered
This clue is a double definition.
'understood' is the first definition.
('gather' can be a synonym of 'understand')
'accumulated' is the second definition.
('gather' can be a synonym of 'accumulate')
'to have' acts as a link.
(Other definitions for gathered that I've seen before include "Drew" , "Surmised" , "The grade (anag.)" , "Accumulated, brought together" , "Concluded from evidence" .)