Sign made by one supporter after Luton's first (5)
I believe the answer is:
libra
'sign' is the definition.
(sign of the zodiac)
'one supporter after luton's first' is the wordplay.
'one' becomes 'i' (Roman numeral**).
'supporter' becomes 'bra' (I've seen this before).
'after' says to put letters next to each other.
'first' suggests taking the first letters.
The first letter of 'luton' is 'l'.
'i'+'bra'='ibra'
'ibra' put after 'l' is 'LIBRA'.
'made by' is the link.
(Other definitions for libra that I've seen before include "Person born under Scales sign" , "Someone born between September 23 and October 22" , "The Scales in astrology" , "Zodiac sign of the scales" , "House" .)