As a saint, there's a vestment for one (5)
I believe the answer is:
alban
'as a saint' is the definition.
I can't judge whether this definition defines the answer.
'vestment for one' is the wordplay.
'vestment' becomes 'alb' (alb is a kind of vestment).
'for' says to put letters next to each other.
'one' becomes 'an' (an apple is one apple).
'alb'+'an'='ALBAN'
'there's a' acts as a link.
Can you help me to learn more?
(Other definitions for alban that I've seen before include "First English Christian martyr" , "First Christian martyr in England" , "-- Berg, composer" , "Saint born at Verulamium" , "Ancient Scottish kingdom" .)