L.,
Your daughter is clingy because she is insecure. You are her family. She doesn't have a father in your home and you made no mention of other siblings. You, as a single mother, have to work full time, so you are not home for 40 hours each week. She needs your time and attention and is not getting it. The clinginess manifests that.
You asked if you are being selfish in insisting on dating and "adult" time at this point in her life. Yes. You are being selfish by insisting on dating at this point in your collective lives and by insisting on "adult" time" that does not include her. At age 14, she is beginning to mature but is still very much a child, and needs your undivided time, love, and attention. As her only functioning parent, your first responsiblity is to her, not to some "honey" or circle of friends. I suggest waiting until she is a bit more mature, (age 18, approx), to worry about your social life and. instead, spend your non-work time providing a quality family life for her.
One of principles involved here is that by fulfilling her needs first, ahead of yours, you will actually be doing the best thing for both of you.
You probably think I am being judgmental. I probably am. Neverthleless, be aware that I am a single mother of a wonderful 26-year-old man and did exactly what I just told you to do. I didn't start dating until my son was a second semester senior in high school (e.g., when he turned 18). (Then the same rules appled to me on dating, curfew, physical relationships, etc. as applied to him, by the way.)I spent my non-work, non-chore time doing things with him. I did not date - at all. That was too destructive to our family unit. One of the things that we did was to plan a major and a minor activity each month in addition to regular talking and doing stuff together. Major activities were defined as camping trips, mountain bike expeditions, backpacking trips, etc., that took half a day or more. Minor activities were defined as movies and such that took three hours or less. (Obviously, specific activities for your daughter would be different and would depend upon what SHE wants to do, not necessarily what YOU want to do.) We didn't have a lot of material wealth, I didn't have a social life, and sometimes we had a messy house. What we did have and still do have is a FANTASTIC relationship! (Note: Neither of us can recall more than about four major contentions/disagreements from the time he was 12 to the present time. And, that is a mouthful for raising a teen-age boy.)
In short, give her the time and attention that she so obviously needs and craves rather than giving her the crumbs of what is left over after your work and self-centered pursuits, and (a) your relationship will improve, and (b) she will probably become less "clingy."
Just another principle to remember: What goes around comes around. Treat her with the same level of courtesy and respect that you want, and you will be amazed at the positive results that follow.