Failing to grab old Express (5)
I believe the answer is:
voice
'express' is the definition.
(I know that voice is a more specific form of the action express)
'failing to grab old' is the wordplay.
'failing' becomes 'vice' (vice can mean a moral failing).
'to grab' is an insertion indicator.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'vice' going around 'o' is 'VOICE'.
(Other definitions for voice that I've seen before include "right to have a say" , "Sound produced in the larynx" , "State" , "Sound of speech" , "Sound produced by humans" .)