Angry look from head of gardeners and inferior (6)
I believe the answer is:
'angry look' is the definition.
'head of gardeners and inferior' is the wordplay.
'head of' indicates taking the first letters.
'and' says to put letters next to each other.
'inferior' becomes 'lower' ('lower' can be a synonym of 'inferior').
The initial letter of 'gardeners' is 'g'.
'from' acts as a link.
(Other definitions for glower that I've seen before include "Angry stare", "burning ember, say?", "Fierce look", "shiner?", "Stare fiercely".)