Healthy, pretentious and polite (12)

I believe the answer is:

wellmannered

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

'polite' is the definition.
(I've seen this before)

'healthy pretentious' is the wordplay.
'healthy' becomes 'well' (associated in meaning).
'pretentious' becomes 'mannered' (I can't justify this - if you can you should give a lot more credence to this answer).
'well'+'mannered'='WELLMANNERED'

'and' acts as a link.

Can you help me to learn more?

(Another definition for wellmannered that I've seen is " Polite".)

I've seen this clue in The Daily Express.

Want a hint initially instead of a full solution? Install my app