Okay, first the bad news. “Kendra” is a totally modern name. There’s no evidence of its existence before the 1940’s, in the US. The best guesses I’ve seen are that it was meant as a sort of feminine form of “Kenneth;” a blend of Kenneth + Sandra/Alexandra, or Kenneth + Andrew; or as a feminine form of “Kendrick.” If there had been any historical name Kendra, it probably would have been a male name — like “Andra,” which is a Scottish boy’s name derived from the Scots pronunciation of Andrew.
“Kendrick” is the kind of name that sounds pretty plausible in several languages; but historically we don’t really see it except in the last name “McKendrick” — which is really “Mac Eanruig” or “Mac Eanruic,” depending on whether you’re going Scottish or Irish. And “Eanruig/Eanruic” is the Gaelic form of the French/English name “Henri/Henry.”
The good news is that obviously, St. Cainnech of Aghaboe (spelled “Kenneth” in Scotland and “Canice” in Ireland) is a real saint and we know a fair bit about his travels and deeds in Ireland and Scotland. He was the son of the poet Lugadh Leithdhearg and his wife St. Maul (or Mella). He is listed as one of the Twelve Apostles of Ireland. Kilkenny, Ireland is named after him, and he built the first church at St. Andrews in Scotland. His feast day is Oct. 11.
The other good news is that there was a Welsh female saint named “Ceindrych” or “Ceindrech.” (It was a reasonably common female name in early sources, too.) A fair number of border Welsh saints with that first syllable “Cein” get it pronounced “Ken” by the Scots. The name didn’t historically turn into Kendra; but it’s close enough to ask her for patronage.
St. Ceindrych, Virgin, is listed as one of the 12 saintly daughters of the famous King of Brytheiniog, St. Brychan. She is associated with churches at Caer Godolor, Thywin in Merioneth, and Llandegwin. No feastday is known.
(Her name may be a different diminutive of the name of one of St. Brychan’s most well-known daughters – the virgin St. Cein, aka Ceinwen (white/Blessed Cein), Keyne, etc. Her feastday is October 8.)
In the land of “close enough,” there’s also the Irish St. Kentigerna or Caintigern, widow and hermit. She was the daughter of Cellach Cualann, King of Leinster, and was named after her mother. She married Feriacus, some sort of petty king. Her brother was St. Comgan of Lochalsh, and her son was St. Fillan of Munster. Her feastday is Jan. 7.
There’s also her more famous male namesake, the monk St. Kentigern aka St. Mungo, patron saint of Glasgow. (Also patron saint of J.K. Rowling’s wizarding world hospital.)
So here are a fair number of nameday patron saint ideas for you.