A little bit in favour of weight (6)
I believe the answer is:
proton
'a little bit' is the definition.
The definition and answer can be both natural objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'in favour of weight' is the wordplay.
'in favour of' becomes 'pro' (being pro a particular cause).
'weight' becomes 'ton' (unit of weight).
'pro'+'ton'='PROTON'
Can you help me to learn more?
(Other definitions for proton that I've seen before include "Atomic constituent" , "Particle in atom nucleus" , "Positive nucleon" , "Elementary particle found in all atomic nuclei" , "just a little bit" .)