Tailored to exist with a radius (7)
I believe the answer is:
bespoke
'tailored' is the definition.
(synonyms)
'exist with a radius' is the wordplay.
'exist' becomes 'be' (synonyms).
'with' means one lot of letters go next to another.
'a radius' becomes 'spoke' ('spoke' can be a synonym of 'radius').
'be'+'spoke'='BESPOKE'
'to' is the link.
(Other definitions for bespoke that I've seen before include "Made to measure" , "Tailor-made" , "Of clothes, made to order" , "Description of tailor" , "Custom-made" .)