FRANCE - This one is a bit of a punt, I had to look it up to make any sense of it - Lady Jessica is a character in Dune (with a reputation for romance - thanks rand al'thor), played by Francesca Annis in the film version. Start of FRANCESCA is FRANCE
PORTUGAL - PORT (dock) U (you) GAL (girl)
ARGENTINA - Joanna is a female form of John (thanks for the pointer rand al'thor). 'Long John' references Long John Silver. Argentina is 'land of silver'
TURKMENISTAN - TURK MEN (men from a 'bird beneath darkness' - see 14A). ISTAN is nearly an anagram of 'nasty' so it could be 'turn nasty'
MEXICO - XI (fourteenth Greek 'four Greek teens' letter), inside an anagram of COME (are coming)? Not completely sure
NIGERIA - Anagram of IREGAIN (I get it back)
TURKEY - A bird. Turkey is south of (beneath) the Black Sea (darkness) (thanks for the hint rand al'thor)
LIBERIA - Means 'Land of the free'
CHILE - Chilli (spicy) or chilly (cold)
IRAN - Anagram of RAIN (precipitation)
CHINA - Anagram of CHAIN which is a unit of length of 22 yards
VIETNAM - Anagram of TELEVISION MAN without the letters from INSOLE
PHILIPPINES - PHILIP (Philip Hammond, British MP for Runnymede) PINES (longs for)
PERU - Anagram of PURE (virgin)
TOGO - To go (takeaway)
BRAZIL - LIZARD backwards, replacing the D
POLAND - Sounds like POLE LAND (land of long sticks). Also you would clean your shoes with POLISH
TANZANIA - TAN (sunburnt) ZANIA (a bit like zany - 'wacky')
WALES - WHALES (giant mammals) without the H (aitch-less which sounds like 'ageless' - thanks for the hint Len / rand al'thor)
CHAD - A paper circle (a word known to no-one until the hanging chad scandal of the 2000 US presidential elections)`
As pointed out by VictorHenry the clues need to be relabelled. Otherwise thank you, I enjoyed that - a few bits of GK and some nice wordplay.