ZERO IN ON SB
UKUSzero in on sb/sth
—Phrasal Verbwithzero(••/ˈzɪərəʊ/verb
(zeroes,zeroing,zeroed)
►to direct all your attention towards a particular person or thing:»
We must decide on our target market and zero in on it.
»Social media allows you to zero in on consumers who'll be receptive to your messages.