The phrase "particular specialty" means having specific expertise or knowledge in a certain area or field. It refers to the specific subject or skill that someone is particularly good at or focuses on. Full definition
In certain states and districts, and in particular specialties like special education or foreign languages, teacher shortages are a recurring fact of life. (edweek.org)
During this time, I have developed a number of particular specialties, including adolescents and families, boys and men, and addiction treatment. (psychologytoday.com)
The technician participates in every phase of patient care; or diagnostic testing under the supervision of the veterinarian, and may have extra training and / or certification in particular specialties. (vet.purdue.edu)