Record trouble with canal — it is vanishing (5)
I believe the answer is:
enter
'record' is the definition.
(enter can mean to enter into a record)
'trouble with canal it is vanishing' is the wordplay.
'trouble with canal' becomes 'enteritis' (inflammation of the alimentary canal).
'it is' becomes 'itis'.
'vanishing' suggests deleting specific letters.
'enteritis' with 'itis' taken away is 'ENTER'.
(Other definitions for enter that I've seen before include "Move into" , "Register formally as a participant" , "submit?" , "Come in - register" , "Enrol" .)