Leave coat by Irish lake (8)
I believe the answer is:
furlough
'leave' is the definition.
(furlough is a kind of leave)
'coat by irish lake' is the wordplay.
'coat' becomes 'fur' (fur is a kind of coat).
'by' is a charade indicator (letters next to each other).
'irish lake' becomes 'lough' (I've seen this before).
'fur'+'lough'='FURLOUGH'
(Other definitions for furlough that I've seen before include "Very unattractive" , "Leave of absence from military duties" , "Temporary leave of absence from military duty" .)