No nicer is wrong English, however you cannot add "-er" to the end of nice.
A nicer word for theft is embezzlement.
nicer
improving
Subsequently, later, next...
Nicer
nicer
nicer, nicest
SACKED
Nicer euphimism for the "f" word.
intellectually challenged: FUNDEMENTAL
Of course it is :) It's nice - nicer - nicest. And remember - there's no such thing as a "real word." If a word is used and people understand it, then it is just as "real" as any word in any dictionary, or any word approved by your English teacher! How else would new words be invented?
There is no one-word anagram. The longest words are relic and nicer.