Those mortified by bad cluemanship? They’re still aware of grouse (3,7)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

A crossword SETTER could be "mortified" by "bad cluemanship" and become RED with embarassment. A red setter is a gun dog, and will go still when birds such as grouse are around to let their master know.