Irish county’s leader absent constantly (6)
I believe the answer is:
always
'constantly' is the definition.
(I've seen this before)
'irish county's leader absent' is the wordplay.
'irish county's' becomes 'galways' (county of Ireland).
'leader absent' means to remove the first letter.
'galways' with its first letter taken away is 'ALWAYS'.
(Other definitions for always that I've seen before include "Perpetually" , "whatever the circumstances" , "Eternally" , "Forever, on every occasion" , "Forevermore" .)