Pervert Dave was disheartened by yucky green tea (10)
I believe the answer is:
degenerate
'pervert' is the definition.
(I know that pervert can be written as degenerate)
'dave was disheartened by yucky green tea' is the wordplay.
I cannot quite understand how this works, but
'by' could be 'at' and 'at' is found within the answer.
an anagram of 'green' is 'gener' which is located in the answer.
The remaining letters 'dee' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for degenerate that I've seen before include "Immoral" , "Rogue" , "In moral or physical decline" , "sink" , "Debased, degraded" .)