Frown on goods starting to be inferior (6)
I believe the answer is:
glower
'frown' is the definition.
(synonyms)
'on goods starting to be inferior' is the wordplay.
'on' is a charade indicator (letters next to each other).
'starting' suggests taking the first letters.
'to be inferior' becomes 'lower' ('lower' can be similar in meaning to 'inferior').
The first letter of 'goods' is 'g'.
'g'+'lower' is 'GLOWER'.
(Other definitions for glower that I've seen before include "Stare fiercely" , "Angry stare" , "Threatening look" , "Fierce look" , "Look thunderous" .)