Crossword Genius

Not in one's own interest (8)

Ross

I believe the answer is:

selfless

I'm a little stuck... Click here to teach me more about this clue!

'not in' is the definition.
Both the definition and answer are adjectives. Perhaps there's an association between them I don't understand?

'one's own interest' is the wordplay.
'one's own' becomes 'self'.
'interest' becomes 'less' (I can't justify this - if you can you should give a lot more credence to this answer).
'self'+'less'='SELFLESS'

Can you help me to learn more?

(Other definitions for selfless that I've seen before include "Considerate" , "Generous" , "Altruistic" .)

I've seen this clue in The Globe and Mail.
Want a hint initially instead of a full solution? Install my app