Old containers in the kitchen holding last of grilled mushrooms (7)

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

Old containers in the kitchen holding last of grilled mushrooms EX- (=old, former) + [<grille> D (“last of” means last letter only) in PANS (=containers in the kitchen)]; to mushroom is to grow or spread, often uncontrollably