Wiktionary
a. (context UK English) fond, or appreciative of
Usage examples of "keen on".
She got it into her head that he was keen on another girland of course as it turned out afterwards, she was quite right there.
A month sounds an age to be crowded with more than forty other men on board a small vessel at anchor most of the time, but I was making the acquaintance of my shipmates, and so keen on learning my new duties that the days were all too short.
Though Hrrubans required slight alterations to the standard saddle to accommodate the difference in their skeletal structure, they were keen on any opportunity to ride their beloved hrrsses.
And if that's your first request, I'm not real keen on finding out about numbers two and three.
She had not stopped to figure out just why she was so keen on going.
I'm not keen on gimmicks but the content was scholarly and comprehensive while engaging the entire class.