Developed skill for working with odd tool they purloined above (4,2)
I believe the answer is:
took to
'developed skill' is the definition.
Although both the answer and definition are past participle verbs, I cannot see how they can define each other.
'working with odd tool they purloined above' is the wordplay.
'working with odd tool they' becomes 'to' (I am not sure about this - if you are sure you should believe this answer much more).
'purloined' becomes 'took' (I've seen this before).
'above' is a charade indicator (letters next to each other) (in a down clue, some letters go above others).
'to' after 'took' is 'TOOK TO'.
'for' acts as a link.
Can you help me to learn more?
(Another definition for took to that I've seen is " Fancied".)