The phrase "a complicated one which" is correct and usable in written English.
It can be used when referring to a complex subject or issue that requires further explanation or detail.
Example: "The problem we are facing is a complicated one which requires a thorough analysis to understand its implications."
Alternatives: "a complex matter that" or "an intricate issue which".
(Just kidding!) Long answer: The question of when lesbians first have sex is a complicated one which, of course, is dependent on the wants and needs of both partners.
It seems — although the issue is a complicated one, which we don't have time to pursue further today — it seems to me more plausible to say morality includes rules not only governing how I treat others but also how I treat myself.
This is especially true if the decision is a complicated one, which results in a temptation to delay it or not make it at all.
The resulting picture is a complicated one in which six of the seven morphologically and ecologically well-defined Moorean species collectively formed two species complexes: 1) P. taeniata and P. exigua; 2) P. suturalis, P. tohiveana, P. mooreana and P. aurantia.
I did a whole set of positions, of movements, signs, like of a rainbow, which is a complicated one, where the fingers move delicately down on a diagonal, that's the sign for "rain," and then the fingers spread up wide, making a large curve, and that's the "bow".
The issue, which is a complicated one, works like this: At the federal level there is a unified tax credit for gifts and estates totaling $675,000 this year.
"It's very simple to realize that in the world of today, which is quite a complicated one and quite a dangerous one, you need friends," said Mogherini, who spoke in Washington at the Carnegie Endowment for International Peace.
Which could make this winter a complicated one for the Redskins.
The story is a complicated one, and one virtue of this book is the clarity with which Mr. Gerson and Mr. Adler explain the legal and political technicalities.
The screenplay, which RZA wrote with Eli Roth, another Tarantino disciple, is a complicated one with a dizzying number of warring clans in feudal China.
