Instir

13 clues
Jailed
Penned
Canned
Locked up
Doing time
Behind bars
Serving time
Jailed, slangily
Serving a sentence
Locked up, slangily
Behind bars, slangily
Doing time, colloquially
Serving a sentence, slangily
Similar answers:
Aains
Abstains
Acareerinruins
Achesandpains
Achesapains
Achirpinginsect
Acreaturewithfins
Acresandpains
Actagainstants
Actins
Addins
Addinsulttoinjury
Addledbrains
Adins
Adjoins
Adkins
Admins
Adropinsnails
Againsam
Against