Enigma
A word or phrase is clued indirectly through wordplay.
ENIGMA (7)
Capitalized, an empire.
When not, a couch or seat.
Palindromic beheadment
Leaves a guy. How neat!
=A. Chemem
The solution: Ottoman. (Removing the string “otto” from the front of the word is a palindromic beheadment.)
Like most flat bases, enigma answers should have dictionary nature, although this is at the editor’s discretion; for example, Atlantic once wrote an enigma on “Juneau mayor” using that each word is a month plus a word for gold.
There is no hard and fast distinction between an enigma and a riddle (which see). Generally, a riddle describes a thing and an enigma a word; riddles have deceptive descriptions, enigmas some form of wordplay. An occasional flat can fairly be classified as either.