What does the cryptic crossword clue "Make changes to it again and there'll be trouble (9)" mean?

The definition is "trouble". The wordplay uses an anagram. anagram of TO + IT + AGAIN = AGITATION; definition: "trouble" The answer is AGITATION.

Make changes to it again and there'll be trouble (9)

Guardian Cryptic #26628 | 11 Across | 2015-07-20 flower