What does the cryptic crossword clue "Being devious, a liar harms a senior officer (3,7)" mean?

The definition is "officer". The wordplay uses an anagram. anagram of A + LIAR + HARMS = AIRMARSHAL; definition: "officer" The answer is AIRMARSHAL.

Being devious, a liar harms a senior officer (3,7)

Daily Mail Cryptic #17212 | 2 Down | 2023-10-23 flower