Way to ignore a measure (3)
I believe the answer is:
rod
'measure' is the definition.
(rod is a kind of measure)
'way to ignore a' is the wordplay.
'way' becomes 'road' (road is a kind of way).
'to ignore' is a deletion indicator.
'road' with 'a' taken away is 'ROD'.
(Other definitions for rod that I've seen before include "Thin straight bar" , "Former measure equal to a quarter of a chain" , "Angler's equipment" , "A few yards" , "See 13" .)