Athena, as concealed in shadow (4)
I believe the answer is:
pall
'shadow' is the definition.
(I've seen this before)
'athena as concealed' is the wordplay.
'athena' becomes 'pallas' ('Pallas' can be a synonym of 'athena').
'concealed' suggests deleting specific letters.
'pallas' with 'as' removed is 'PALL'.
'in' is the link.
(Other definitions for pall that I've seen before include "Cloth over a coffin - become insipid" , "A dark cover; cease to interest" , "Cloth spread over a coffin" , "Become tiresome" , "Become less interesting" .)