Their

5 clues
Pronoun
Possessive
Possessive pronoun
Possessive adjective
Gender-neutral possessive
Similar answers:
Aaronbirth
Aattheopera
Aattheraces
Abath
Abathingbeauty
Abdominalthrust
Abenchinthepark
Abernathy
Abguthrie
Abidebytherules
Abidingfaith
Abirdinthehand
Abirdinthesand
Abitontheside
Abookofthebible
Abother
Aboutazoofilledwith
Aboutfaith
Abouther
Abouthisize