Dry — just about dead as well (8)
I believe the answer is:
secondly
'well' is the definition.
Both the definition and answer are adverbs. Perhaps there's an association between them I don't understand?
'dry just about dead' is the wordplay.
I cannot really understand how this works, but
'dry' could be 'seco' (I've seen this before) and 'seco' is found within the answer.
'dead' could be 'd' and 'd' is located in the answer.
This may be the basis of clue (or it may be nonsense).
'as' acts as a link.
Can you help me to learn more?
(Other definitions for secondly that I've seen before include "Not in first place" , "Next after firstly" .)