Tailor ready to accept a good length
I believe the answer is:
yardage
'length' is the definition.
(I've seen this before)
'tailor ready to accept a good' is the wordplay.
'tailor' is an anagram indicator (I've seen this in other clues).
'to accept' indicates putting letters inside.
'good' becomes 'g' (abbreviation).
'ready' anagrammed gives 'yarde'.
'a'+'g'='ag'
'yarde' placed around 'ag' is 'YARDAGE'.
(Other definitions for yardage that I've seen before include "Distance - day rage (anag)" , "Distance sometimes measured in paces" , "Quantity of fabric" , "Measurement of length" , "Gay dear (anag.)" .)