Her face wore an agonized look as if she was going through inner turmoil.

agonized 是动词 agonize 的过去分词形式，agonize 由词根 agony（极度痛苦）加上动词后缀 -ize 构成，意思是"使痛苦、折磨"。agonized 在这里作形容词，表示"表现出极度痛苦的"。