A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

eat a peck of dirt • eat dirt
eat a peck of dirt—put up with insult and abuse; submit to
humiliating treatment: In times of revolution a good many
pecks of dirt have to be eaten.
eat dirt—(coll.) 
1
. = eat a peck of dirt: Lord Fitzurse made
up for the dirt which they had been eating by the splendor of
his entertainment. 2. (also: eat someone’s dust) trail another
competitor in a race: He was the leader in the bike race until
he ate dirt and was passed by almost everyone else.
See also: dirt-eater / dirt-eating.
eat away • eat out
eat away —eat continuously; eat as much as one likes: Be
prepared to spend at least two hours chatting and eating
away, relishing every minute of Fran’s delicious German cook-
ing.
Note: 
The expression does not correlate in meaning with the
phrase eat away from home— have one’s meals in cafeterias, etc.
rather than at home: When eating away from home, people eat
either larger quantities or higher calorie foods.
eat out—eat in a restaurant, etc. instead of at home: Some-
times eating out can be cheaper than buying a weeks worth of
groceries. Cf.: eat in — eat or dine at home: I would certainly
recommend the hotel to people who prefer to eat in and cook
for themselves.
eat away at something • eat away something
eat away at something —destroy smth. gradually: Attempts
have been made to stop the Sphinx from eroding even more.
The blowing sands in the desert are gradually eating away at
it.
eat away something —
1
. destroy smth. by eating: The mon-
keys had eaten away most of the mangroves, and the only ones
that remained were shielded by steel cages. 2. destroy smth.
by chemical action: Structures such as bridges, buildings, and
monuments are also at risk, as they can be literally eaten away
by the acid.