As Romans Do

a cryptic puzzle by Emily Cox and Henry Rathvon

Solution
A number of clue answers must be modified in a certain way before they will fit in the diagram. These altered entries are examples of 22 Across (which is itself appropriately treated in the diagram). Clue answers include four proper words, two less-than-common words (36 Across and 24 Down), and a variant spelling at 25 Across. Modified answers include one proper noun and three two-word phrases.

Across

  • 1.
    Flier in plane's beginning to zip right (6)
  • 6.
    Circle small South American mountain (4)
  • 10.
    Incredible informant takes track back (4)
  • 11.
    A steamship looping through spot of great depth (5)
  • 13.
    Aliens repulsed the head of France (4)
  • 14.
    Fraction of shelter getting hot (5)
  • 15.
    Fat-skinned pig has port (8)
  • 16.
    Devotees drink pints (6)
  • 18.
    Dodger error gets ruled hit (6)
  • 21.
    Course down around Louisiana (5)
  • 25.
    Nordic melody, Wagner's fourth (5)
  • 29.
    Heading off tardy and in high spirits (6)
  • 30.
    Italian locale gives most of aid to island (6)
  • 32.
    Military police strangled by loopy snake collector (8)
  • 33.
    So. Cuba's leader forsakes armistice (4)
  • 34.
    Sound of ocean was stormy (4)
  • 35.
    Youngster dressed toplessly (3)
  • 36.
    Registered nurse pockets one Japanese coin (3)
  • 37.
    Club specifically for people generally (4)
  • 38.
    Turning fiery, present puzzle (6)

Down

  • 1.
    Uncouth fellow, large and unpopular (4)
  • 2.
    The debut of Trevor Howard in a Disney film (4)
  • 3.
    Traffic sign raised around 4 turns (6)
  • 4.
    Priests left a religious service unfinished (5)
  • 5.
    Checks about 1,000 chair parts (8)
  • 6.
    Say, "Pretty ribbon, sweetheart" (4)
  • 7.
    Woman's keeping on rising from a church council (7)
  • 8.
    Garbage truck's first to get reckless (5)
  • 9.
    Pirate goes back, packing a fifth of brandy (two words) (3,3)
  • 12.
    Horse carriages finally ready for driving (5)
  • 17.
    Fold full-page illustration in a book audibly (5)
  • 19.
    Alumnus unhesitatingly breaks bones (5)
  • 20.
    Guy passing out with removal of G string (8)
  • 22.
    Get capsized in one hide vessel (7)
  • 23.
    Foolishly pelt rat with baloney (7)
  • 24.
    Vocally accede to crown vetch (6)
  • 25.
    Sanctioned sounds in hearing range (5)
  • 26.
    Try for the relocation of Persia (6)
  • 27.
    Pad some medicine that hurts (6)
  • 28.
    Clothes for wife are tailored (4)
  • 30.
    Change beginning of PM? (5)
  • 31.
    Ruins Latin king in speech (6)