I would say 专科门诊 for 专业门诊. You can take Clinic of special section or specialist out-patient according to your detailed context...

See following for ref.:
专科门诊
Clinic of special section
专科门诊 Clinic of special section. 高血压专科Hypertension special section. 2. fang2000fang.blog.sohu.com
Famous Doctors Clinic
针灸门诊. Acupuncture Clinic. 380. 1.4. 532. 为民服务门诊. People Serving Clinic www.cse.org.cn
专科门诊部
Special Clinics
专科门诊部, Special Clinics, 15, 87, 116, 108. 六急救中心站, Firstaid Centres, 5 www.shanxigov.cn
specialist out-patient department
specialist outpatient department. 專科門診部. specialist outpatient service. www.csb.gov.hk

Jukuu Bilingual Sentence Searcher

There were 1209751 discharges, 8508642 specialist out-patient attendances and 833355 general out-patient attendances.
年内,出院病人有1209751人次,专科门诊就诊者有8508642人次,普通科门诊有833355人次。
-- life-汉英
geriatric specialist out-patient service [Hospital Authority]
老人专科门诊服务〔医院管理局〕
-- 英汉-翻译参考[网络]
TEDA Hospital has over40 clinics and180 sickbeds.
泰达医院现有40多个专科门诊,病床180张。