For her, finding a way through is more arduous (6)
I believe the answer is:
harder
'is more arduous' is the definition.
('hard' can be a synonym of 'arduous')
'for her finding a way' is the wordplay.
I cannot quite see how this works, but
'her' could be 'de' and 'de' is present in the answer.
'a' is within the answer.
This may be the basis of the clue (or it may be nonsense).
'through' acts as a link.
Can you help me to learn more?
(Other definitions for harder that I've seen before include "More tough or difficult" , "More solid" .)