Sample case under reflection of work counter (6)
I believe the answer is:
oppose
'counter' is the definition.
(I've seen this in another clue)
'sample case under reflection of work' is the wordplay.
'case' suggests removing the centre.
'under' is a charade indicator (letters next to each other).
'reflection of work' becomes 'oppo' (I can't justify this - if you can you should give a lot more credence to this answer).
'sample' with its middle removed is 'se'.
'se' after 'oppo' is 'OPPOSE'.
Can you help me to learn more?
(Other definitions for oppose that I've seen before include "Resist; play against" , "Resist (someone)" , "Counter" , "Resist, be hostile to" , "match" .)