はっきり勉強する

Use hakkiri as an adverb before the verb benkyou suru. You can add the particle to to make it hakkiri to. This adds a bit more emphasis. It describes the *manner* of your effort. Use it when you want to sound intentional. It sounds like you have a solid plan. It’s a great way to show commitment.

Use this when you finally pick a specialty. Maybe you are texting a friend about your goals. 'I’m going to clearly study business Japanese.' Use it in a meeting with a teacher. It shows you aren't just drifting. It’s perfect for New Year's resolutions. Use it when you feel motivated and organized. It fits well in a self-improvement context.

Don't use this for 'studying hard' in general. For that, use shikkari or isshoukenmei. If you are just browsing Wikipedia, don't use it. It’s not for passive learning or 'just looking.' Avoid it if your study plan is messy. If you are exhausted and can't focus, it's the wrong word. It implies a sharp, bright mental state.

Japanese culture places a high value on keikaku (planning). Being vague about your intentions can be seen as weak. Using hakkiri shows you have a 'strong core.' It reflects the 'ganbaru' spirit but with more intelligence. It’s about being 'meikaku' (clear/distinct) in your personal growth. This phrase has become more popular with productivity culture.

hakkiri to benkyou suru is the most common variation. You might also hear mokuhyou wo hakkiri saseru. This means 'to make your goals clear.' You can also use hakkiri saseru with other verbs. For example, hakkiri kimeru means 'to decide clearly.' These all share the same 'sharp focus' vibe. They make you sound like a pro.