Fetching details from the dictionary...
to make narrower; to shut (an umbrella); to shrug (one's shoulders); to purse (one's lips)
寒さに肩を窄めて歩いた。
I walked hunching my shoulders against the cold.
彼女はそんなに肩を窄める必要はない。
She doesn't need to hunch her shoulders like that.
批判されると彼はいつも肩を窄めている。
Whenever he's criticized, he always hunches his shoulders.