What does the cryptic crossword clue "Betty and Carl developed campaign slogan (6,3)" mean?

The definition is "slogan". The wordplay uses an anagram. anagram of BETTY + CARL = BATTLECRY; definition: "slogan" The answer is BATTLECRY.

Betty and Carl developed campaign slogan (6,3)

Daily Mail Cryptic #16721 | 5 Down | 2021-12-03 flower