着てた

was wearing, wore

→ 着る
wear, put on + Te-form (conjunctive) + Past tense
verb · past indicative Rare #39,103
was wearing, wore Informal past form of 着ていた.
JA: 昨日、赤いシャツを着てた。
EN: I was wearing a red shirt yesterday.
Conjugation of 着る
Indicative past
着ました着てた

トム着てたのは青いセーターじゃなかった

What Tom was wearing wasn’t a blue sweater.

この着てた奴はがなかった

The guy wearing this armor was out of luck.

— 荒野の用心棒 (1964)

普段は修道院着てた

It’s what I usually wore at the convent.

— 燃ゆる女の肖像 (2019)

トムみすぼらしい服を着てた

Tom was wearing shabby clothes.