Put weight on! (6)
I believe the answer is:
stress
'put weight on' is the definition.
(I've seen this before)
'on' is the wordplay.
I cannot quite see how this works, but
'on' could be 're' (regarding) and 're' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for stress that I've seen before include "Underline - tension" , "Emphasize" , "result of being overworked" , "nervous tension" , "suffering" .)