 He completed a degree in Education at Trinity College, Dublin, graduating in 1987, before joining the Irish Army as a cadet in 1989.In 1995, Clonan deployed to South Lebanon as an officer commanding Irish troops under the United Nations Interim Force in Lebanon (UNIFIL) mission in that country.Clonan's deployment to Lebanon coincided with the Israeli punitive Operation 'Grapes of Wrath' against Hizbullah which culminated in the massacre of refugees at the village of Qana in April 1996.