Here's what is going on. I am targeting the keyword "sex toys for women". I have a high page rank link that is using the anchor text "sex toys for women" and is linked to mydomain.com/sex-toys-for-women. After 6 weeks of this link mydomain.com (NOT mydomain.com/sex-toys-for-women) is ranking for the term. In this case would I be better to change the link to mydomain.com so all of the link juice is flowing to the page that is ranking? I am a bit nervous about this disrupting all of the other rankings I have achieved.
My guess would be that your home page has the term sex toys for women on it. Try taking it off the home page. Also build some more low pr links with sex toys for women anchor text to the sub-page so google knows without a doubt which page is more relevant. If you don't have the term on your home page then it is probably it's authority for just the term sex toys. In that case just keep building for "sex toys for women" to the sub page.
I wouldn't change anything. I mean the relevant page is ranking for the term you wanting. maybe place a good direction link on the page to send people to the home page. This way you don't hamper your efforts and loose your ranking.
You need to build links to the main page that are 70% to 30% to inner page, otherwise Google might wonder why your inner page has PR and your home page hasn't.
Don't change it from inner page it will automatically come from home after some time, you just try to target on inner page because a product is on that page so user have to go directly on that page, all pages are linked to home page so if you target internal page then it will automatically come from home page don't worry.