Fetish: a form of sexual desire in which gratification is linked to an abnormal degree to a particular object, item of clothing, part of the body, etc.
Based on the definition provided by Google, I don't think it's too far off the mark to say that yes, crossdressing is a fetish for many in the community, whether they like to admit it or not. For many, wearing pieces of female clothing usually results in sexual arousal. I'll be lying if I said that dressing up in female attire doesn't get my engine revving as well. It is also one of the reasons why I think the urge to crossdress increases exponentially after the onset of puberty, when sexual desires emerge due to the new chemical cocktails swirling in the body. The desire to "get off" while crossdressed starts around that age too.
I'm not saying that crossdressing is a fetish for everyone in the community. There are many reasons why one decides to crossdress and not all of them have their roots in deriving sexual pleasure. Some do it because it is fun, some do it to to feel whole and complete, etc. Our motivations to crossdress may also change as we grow older and more experienced as well; it could start off as a sexually stimulating activity, but the fires mellow over time and one crossdresses because it is a relaxing, fun activity to do. Shopping as a girl is undeniably more enjoyable by MILES compared to shopping as a guy.
For crossdressers, it is important to realise that there is nothing wrong to feel turned on by wearing women's clothes (there is sometimes a lot of post-dress-up / post-release guilt involved). Just because something is a fetish does not mean that it is a perversion. These two words have a tendency to be confused together. As humans, we all have our different personal tastes and kinks. For a more mainstream example, guys like it when ladies with long legs show off their figure in short, tight bodycon dresses and high heels. Isn't that a fetish too? But it is never considered a perversion to have this preference (unless you're living in a super conservative part of the world, which in Singapore, we are not).
Perhaps in the definition above, "abnormal degree" is the part that we crossdressers need to be conscious of. It differentiates a healthy kink from an addiction that consumes your everyday thoughts, to the point of affecting your ability to function properly day to day as another member of society.
There's nothing wrong if crossdressing turns you on. But always remember, everything in moderation 😉