動詞
(有權勢嘅人)幫住某人,令佢唔驚其他人 (someone with power) to back somebody up; literally, to support one's waist
個孫成日有嫲嫲幫佢撐腰,搞到而家成日唔聽父母話。
个孙成日有嫲嫲帮佢撑腰,搞到而家成日唔听父母话。
go3 syun1 seng4 jat6 jau5 maa4 maa4 bong1 keoi5 caang1 jiu1, gaau2 dou3 ji4 gaa1 seng4 jat6 m4 teng1 fu6 mou5 waa6. The grandchild always has his grandma to back him up, turns out he barely listens to his parents now.
Definitions (Wiktionary)
verb
to back (someone); to be behind (someone) for support