Expect going topless will reveal evidence of neglect (4)
I believe the answer is:
rust
'evidence of neglect' is the definition.
(sign something hasn't been cared for)
'expect going topless' is the wordplay.
'expect' becomes 'trust' (trusting is a kind of expecting).
'going topless' means to remove the first letter.
'trust' with its initial letter taken off is 'RUST'.
'will reveal' acts as a link.
(Other definitions for rust that I've seen before include "Reddish-brown coating formed on iron by moisture" , "Reddish-brown coating formed on metal by damp" , "Reddish-brown coating formed on metal by moisture" , "Fungal disease of plants" , "Reddish-brown colour" .)