What does the cryptic crossword clue "It ran Nato ragged as an expression of frustration (9)" mean?

The wordplay uses an anagram. anagram of IT (synonym="IT") + RAN (synonym="RAN") + NATO (synonym="NATO") = TARNATION The answer is TARNATION.

It ran Nato ragged as an expression of frustration (9)

Guardian Cryptic #29161 | 25 Across | 2023-08-29 flower