狂 (KYŌ, kuru(u): lunatic, mad; suffix meaning “enthusiast” or someone with a certain mental abnormality)
彼はまったくのゴルフ狂だ。
Kare wa mattaku no gorufukyō da.
He’s quite crazy about golfing.彼 (kare: he)
まったく, also written 全く (mattaku: really, truly, entirely)