Have one? I'll be blessed if I will! (6)
I believe the answer is:
sneeze
'have' is the definition.
The definition and answer can be both related to bodily activities as well as being verbs in their base form.
Perhaps they are linked in a way I don't understand?
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for sneeze that I've seen before include "Symptom of cold" , "Explosive nasal release" , "reason for blessing" , "Audible and uncontrolled expulsion of air through nose and mouth" , "Sign of the common cold" .)