What does the cryptic crossword clue "A Mexico neighbour, a month back, shot at meal (9)" mean?

The wordplay uses an anagram. anagram of AUG (synonym="month") + AT (synonym="AT") + MEAL (synonym="MEAL") = GUATEMALA The answer is GUATEMALA.

A Mexico neighbour, a month back, shot at meal (9)

Guardian Cryptic #29124 | 21 Across | 2023-07-17 flower