Sloth unknown in East, captured by young woman (8)
I believe the answer is:
laziness
'sloth' is the definition.
('laziness' can be a synonym of 'sloth')
'unknown in east captured by young woman' is the wordplay.
'unknown' becomes 'z' (algebra).
'east' becomes 'e' ('E' can be a synonym of 'east').
'captured by' is an insertion indicator.
'young woman' becomes 'lass' (lass is a kind of young woman).
'z'+'in'+'e'='zine'
'zine' going inside 'lass' is 'LAZINESS'.
(Other definitions for laziness that I've seen before include "Lethargy" , "Idleness" , "Indolence, sloth" .)