Escape into valley and remove unwanted coat (7)
I believe the answer is:
descale
'remove unwanted coat' is the definition.
(as removing a layer of limescale)
'escape into valley' is the wordplay.
'escape' becomes 'esc' (Escape key on a keyboard).
'into' means one lot of letters goes inside another.
'valley' becomes 'dale' (dale is a kind of valley).
'esc' put inside 'dale' is 'DESCALE'.
'and' is the link.
(Other definitions for descale that I've seen before include "Remove lime deposit" , "Remove lime (from kettle, boiler etc.)" .)