Pong, a not quite fresh kind (6)
I believe the answer is:
humane
'kind' is the definition.
('humane' can be similar in meaning to 'kind')
'pong a not quite fresh' is the wordplay.
'pong' becomes 'hum' (I've seen this before).
'not quite' means to remove the last letter.
'fresh' becomes 'new' ('new' can be a synonym of 'fresh').
'new' with its final letter removed is 'ne'.
'hum'+'a'+'ne'='HUMANE'
(Other definitions for humane that I've seen before include "Characterised by kindness" , "Kind and sympathetic" , "Kind and liberal" , "Kind and civilised" , "Kindly and compassionate" .)