Pale like one prone to brooding (5)
I believe the answer is:
ashen
'pale' is the definition.
(synonyms)
'like one prone to brooding' is the wordplay.
I cannot quite understand how this works, but
'like' could be 'as' and 'as' is located in the answer.
The remaining letters 'hen' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ashen that I've seen before include "Very pale, with shock or fear" , "Bloodless" , "White-faced" , "Pale (faced)" , "Drained of colour" .)