The usual top quality puzzle from Phi, with all clear in the end. Held up a little by two musical clues (9 ac, 4 dn) crossing, but got there in the end. In line with recent Indy trends, there is a theme. I refer to it after the clue explanations.
Solving time: 20 mins
* = anagram
ACROSS
9 OOMP(A)H Oomph = much effort, vitality
10 SAG O
11 MA GNIFICAT (facing it)* Song of Mary, based on New Testament.
12 C (ENS) OR Very good with misleading join at “Banner/headline Last letters of “headline in Times” in Cor. Good to see the papers acknowledging each other’s existence.
15 CHAIN REACTION A very good cryptic definition.
23 Jacques TATI Known for Monsieur Hulot’s Holiday and more. Hidden in naTATIon (6 down), but I guessed it before getting to 6 down and pencilled it in.
24 UNTIED Tricky and the last I entered. The whole clue has to be read as the definition i.e. it’s the opposite of joined. Cryptically it means joined = united. It’s taken the opposite way – it becomes ti and you get untied.
25 TATTOO E (end of IndependencE) D (Day)
DOWN
1 (o)NE W AGE
4 HOL(I)ST Gustav Holst (1874-1934) best known for the Planets – I was looking for is to go in at first, with a four letter composer.
5 IMPI(ous) Warriors seen in Zulu country and frequent visitors to crossword grids. 4/7 = more than half
6 NA(TA)TION Formal word for swimming – used in clue for 23 ac.
14 EMI G RATION allocation shows it’s ration not rating
15 CRA(SHIN)G
18 E (S) CUD O O (old) DUCE (European leader – the title assumed by Italian dictator Mussolini) around S = second. All reversed. Portuguese currency replaced by the euro in 2002.
20 NUT MEG Again all reversed gem tun
22 ENID Dine(d) – another reversal
Theme: Top and bottom rows spell NOTHIN/G DOING