An excellent puzzle, with great manipulation of letters in anagrams in many cases to give &lit clues where the whole clue, as well as providing the wordplay, also gives the definition of the answer. The highish proportion of anagrams made it a reasonably fast solve for me, 22 mins.
* = anagram < = reversed
ACROSS
1 SATELLITE TOWNS (Estates will not)* The first &lit.
12 ENCODES D (diameter) for R (radius) in encores (repeats). You know a diameter is twice the length of a radius, don’t you?
13 TR (ACHE) A art< The windpipe.
14 STAVE, I think. This was my last entry, toyed with SOAVE for a bit, but I think it’s a double reference to wood used in barrels and staves in musical bars.
16 APPLE JACK The Garden of Eden’s temptation
19 FRESCOERS (socer refs)* Half-hearted = only one of the cs
20 TITHE (i = one tenth less n = number)* Subtle
25 HO (T SP) TO tsp = teaspoon(ful)
29 SELF-EXPRESSION This, if I’ve interpreted it right, refers to Descartes’ famous saying – Cogito ergo sum (Latin) = I think, therefore I am
DOWN
1 AUTOCLAVE (a cute oval)* Used in cooking and also in science.
3 E(ng)LAND
6 TEST AMEN T Another &lit
7 WRATH hidden
8 SKY LARK
9 LEVEES (sea-level)* less al(l) Another excellent &lit
16 AN TIP AS TO
21 E STEEM Meets<
23 NASA L(middle letter)
24 (An) TWERP
26 TRAMS smart<
The last word for me too was STAVE. While I do know that ‘staves’ are thin slats of wood forming the sides of a barrel, the latter part of the clue eludes me.
A dictionary lookup reveals that ‘stave’ is also a crosspiece between the legs of a chair; so is the reference to bar chairs? Not too sure.
Oh, I didn’t think of musical bars.