Potential case of neglect follows behind schedule (6)
I believe the answer is:
latent
'potential' is the definition.
('latent' can be similar in meaning to 'potential')
'case of neglect follows behind schedule' is the wordplay.
'case of' suggests removing the centre (outsides of).
'follows' means one lot of letters go next to another.
'behind schedule' becomes 'late' (I've seen this before).
'neglect' with its centre removed is 'nt'.
'nt' put after 'late' is 'LATENT'.
(Other definitions for latent that I've seen before include "There but not yet effective" , "Hidden, not manifest" , "Indiscernible" , "Existing but not yet active, say talent" , "Existing but not yet active or developed" .)