Solutions

ACROSS
1 Saussure.
SAUSSURE (so sure hom.)
5 Temper.
TEMP+ER (re rev.)
9 Peter Pan.
PE(TERPA)N
10 Listed.
LI+STED (Ted's anag.)
11 Oleander.
O+LEANDER
12 Ostler.
(hidden)
14 Other ranks.
O+THE+R+RANK+S
18 Choir stall.
CHOIRS+TALL
22 Retina.
(anag.)
23 Gujerati.
GUJ+ERATI (jug rev. & irate anag.)
24 Edison.
(anag.)
25 Announce.
ANN+OUNCE
26 Thebes.
THE(B)ES (these anag.)
27 Trial run.
TRIAL+RUN (NUR rev.)


DOWN
1 Siphon.
SIP+H+ON
2 Untied.
UN+TIE+D
3 Spring.
(two meanings)
4 Real estate.
REAL(E)S+TATE
6 Emissary.
E+MISS+ARY (Ray anag.)
7 Pot plant.
(straight cryptic)
8 Red Cross.
RED+CROSS
13 Fell-runner.
FELL+RUNNER
15 Scarlett.
S(CARL)ET+T
16 Voltaire.
VOLT+AIRE (vault hom.)
17 Francome.
FRA(NCO)ME (con anag.)
19 Verona.
VER(ON)A
20 Tanner.
(two meanings)
21 Wigeon.
WI(GEO)N