First one subtracted from odd number — becoming this? (4)
I believe the answer is:
even
'first one' is the definition.
Both the definition and answer are adjectives. Maybe you can see an association between them that I don't see?
'subtracted from odd number becoming this?' is the wordplay.
I cannot really see how this works, but
'number' could be 'v' (V is an example) and 'v' is found in the answer.
The remaining letters 'een' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for even that I've seen before include "happening to take time off?" , "Smooth, level" , "Level, par" , "Level, calm" , "Commensurate" .)