In circumstances, trying descent (8)
I believe the answer is:
ancestry
'descent' is the definition.
('ancestry' can be a synonym of 'descent')
'in circumstances trying' is the wordplay.
'in' says the answer is hidden in the clue.
'ANCESTRY' is hidden within 'circumstances trying'.
(Other definitions for ancestry that I've seen before include "Blood line" , "Genealogy" , "Lineage" , "Line of forebears" , "Any crest (anag.)" .)