verb + 一 + verb is a structure. 想一想、看一看、说一说、听一听、打一打 etc. we use this structure when we want to express that what we want to do is not hard. for example, 妈，我想打一打篮球。------------ you want to tell your mother that u want to play basketball, but u think that ur mother might not let u go, so u say: 打一打 to express that it's just playing basketball, not a big deal.

means"think"，让我想一想means“ let me think”

have a think

u r right

The phrase "想一想" refers to "think trice", "think about it", or "remind something". The same verb structure (V.-one-V.) could be applied on other sensory verbs like 聽一聽, 看一看, and 聞一聞 etc.