懂眼

懂眼	dǒng yǎn	(coll.) to know the ropes / an expert
懂	dǒng	to understand / to comprehend
眼	yǎn	eye (CL:只,双) / (often used with 一) a look; a glance / small hole / (bound form) salient point / classifier for wells, cave-dwellings etc