Here are some constructors’ comments about The Nation’s Puzzle #3233.
9A EULER Mathematician’s fuel ship in sound (5)
Leonhard Euler was one of the greatest and most prolific mathematicians of all time. And yes, it is pronounced “oiler.”
25A CEASE-FIRE Truce in argument about error with cashier (5-4)
To cashier someone is to fire them.
26A PILAF Rice course with pass/fail mix-up (5)
Not so easy to define this word without tipping your hand. Given the academic tenor of the wordplay, which was irresistible, the surface was intended to refer to a course at Rice University in Houston. And yet we doubt many solvers were fooled.
7D PISCES Postpone first bit of seasoning for fish (6)
We usually try to limit ourselves to well-mixed anagrams, but sometimes a single letter shift is interesting—for example, when (as in this case) the pronunciation changes substantially.
13D STARCHIEST Superlatively formal holy men flanking Veronica’s friend (10)
The “holy men” are two instances of ST (saint).
20D DOUBLET How to turn a tire into something to wear (a garment) (7)
If you double the T in “a tire” you get “attire.”
Would you have accepted this clue if we hadn’t included the part in parentheses? That would have forced “something to wear” into double duty. I wouldn’t have minded.—HP
19A INDIA Gandhi abjures resistance for The Nation (5)
24D SIKH Loudly search for Indian believer (4)
Well, look at that—the solution to one clue shows up in another. We try to be very scrupulous about never doing that, but even Homer nods. In fact, we didn’t notice it until just now. Sorry about that…