Answer: oldnag

AnswerCrossword Clue
OLDNAG

Racing has-been

OLDNAG

Washed-up horse

OLDNAG

Horse that has seen better days

OLDNAG
Racetrack senior citizen
OLDNAG
Candidate for the proverbial glue factory
OLDNAGTrack has-been
OLDNAGRacetrack has-been
OLDNAGUnlikely derby winner
OLDNAGHorse-track has-been
OLDNAGHas-been of a horse