| ACRONYMS | Words formed from the initials of others (8) |
| ACROSTIC | Word formed from the initials of other words (8) |
| ACRONYM | NATO and laser are examples of this word formed from the initials of other words |
| ANAGRAMS | Words formed from the letters of another (8) |
| ACIDTEST | Ordeal ... and a hint to the initials of the answers to starred clues |
| PERICARP | Part of a fruit formed from the wall of the ripened ovary (8) |
| ANAGRAM | Word formed from the letters of another (7) |
| LAYSINTO | Phrase meaning "attack with words" formed by an anagram of "saintly" + O: 2 wds. |
| CUTE | A word formed from the letters which symbolise the chemical elements copper and tellurium (4) |
| MONOXIDE | Carbon _ _ _ _ _ _ _ _ , a colourless, odourless, very toxic gas formed from the incomplete combustion of carbon (8) |
| NEWORDER | Blue Monday band that was formed from the remnants of Joy Division |
| ESSO | Gas brand whose name comes from the initials of Standard Oil |
| COLDOPEN | Start of each "S.N.L." episode ... or a hint to the initials of the words in 17-, 24-, 35- and 47-Across |
| TANDU | Letters Of the alphabet, which are, fittingly for 2021's first crossword, the initials of the theme entries |
| JK | "Rowling" along: The initials of the writer of the Harry Potter books (or what a texter types when she's "just kidding") |
| GAL | Old fashioned term of girl (or the initials of the little prince of Cambridge) (3) |
| JOHNNYHART | Creator of the classic comic strip whose title is the initials of the *clue answers |
| ABBA | Pop group whose name derives from the initials of its members' first names |
| IKEA | Store chain whose name partly comes from the initials of its founder Ingvar Kamprad |
| PARTICIPLE | Word formed from a verb (10) |
