Frown on goods starting to be inferior (6)
I believe the answer is:
glower
'frown' is the definition.
('glower' can be a synonym of 'frown')
'on goods starting to be inferior' is the wordplay.
'on' means one lot of letters go next to another.
'starting' says to take the initial letters.
'to be inferior' becomes 'lower' ('lower' can be similar in meaning to 'inferior'**).
The first letter of 'goods' is 'g'.
'g' put next to 'lower' is 'GLOWER'.
(Other definitions for glower that I've seen before include "Stare fiercely" , "Angry stare" , "Threatening look" , "Fierce look" , "Look thunderous" .)