A few Thai-related facts! Siamese fighting fish is called ปลากัด 'pla kat' in Thai; ปลา means fish and กัด means to bite (i.e. to fight, figuratively). The United States subprime mortgage crisis was also dubbed specifically by Thai journalists as "Hamburger crisis", analogous to "Tom Yam Kung crisis".
A word that describes itself is called autological word or autonym (e.g., "word" is a word, "English" is an English word). The grid spanner 39A has struck me with the above quality so I started from it and looked for other autonyms. 18A and 60A are not only symmetrical but also concern linguistics duo: semantics and syntax respectively. Hope you like clues for 25A, 43A, 12D and 28D!