How do you give written credit in APA, to an author when you are paraphrasing an article, without turning the paraphrasing sentence into an in-text...

When using the information or ideas of another source in a paper, you must always cite the source.  American Psychological Association (APA) style is a standard citation style for social sciences.  Paraphrasing with any citation style can be difficult, but it must include an in-text citation.  The style of citation will vary depending on how you, the author, introduce the original work.

To avoid using any parenthesis in your paper, you will need to introduce the author, title and year of the originally published information.  This is the only way to avoid any in-text citation markings.  For example: 

"Microbiologist Larry Sten argues in his 1999 book Crossing Over, animal species...".

You can also cite just the author, but you will need to include the year in parenthesis:

"Microbiologist Larry Sten (1999) argues...".

Paraphrasing and summarization of published material is a very difficult line to balance.  To keep from falling into plagiarism you need to avoid using too many words matching the original authors.  This includes uncommon phrases or descriptive phrases.  It should be noted page numbers are not required in APA style, but you may want to use them to help the reader pinpoint the exact location in a large work.

"Microbiologist Larry Sten (1999, pg. 456) argues...". 

Regardless of how you introduce the information in the main body of the paper, you must include the proper citation in the Works Cited or Bibliography page!