Answer: hardcore

AnswerCrossword Clue
HARDCOREDedicated
HARDCOREDyed-in-the-wool
HARDCOREUnswervingly committed
HARDCOREUncompromising
HARDCOREAvid
HARDCOREUnyielding element of a group.
HARDCOREUnyielding nucleus of a group
hardcoreunyielding / a style of rock music