Yes, you can have it professionally edited but editorial help can only be used for copyediting and proofreading (not substantive editing). Your supervisor should provide editorial advice in regards to substance and structure (an editor can't do this), language, and use of illustrations and tables.
You should consult your faculty to see if you have research funding available from your allowance for professional editing. If you do decide to engage the services of an academic editor, ensure they are a member of the Institute of Professional Editors (IPEd) as they will know the level of editorial intervention allowed.
For more information about professional editing see Thesis Submission.