Sly subsidiary worker (9)
I believe the answer is:
underhand
'sly' is the definition.
(I've seen this before)
'subsidiary worker' is the wordplay.
'subsidiary' becomes 'under' (I can't explain this - if you can you should give a lot more credence to this answer).
'worker' becomes 'hand' (hand is a kind of worker).
'under'+'hand'='UNDERHAND'
Can you help me to learn more?
(Other definitions for underhand that I've seen before include "Sneaky" , "Reporting to worker" , "delivery may be so made" , "Crafty" , "Done in sly or secret way" .)