Map used by a piper touring central Ireland (4)
I believe the answer is:
plan
'map' is the definition.
(I've seen this in other clues)
'a piper touring central ireland' is the wordplay.
'a piper' becomes 'pan' (I've seen this in another clue).
'touring' is an insertion indicator (touring can mean going round).
'central' says to take the centre.
The central letter of 'ireland' is 'l'.
'pan' placed around 'l' is 'PLAN'.
'used by' is the link.
(Other definitions for plan that I've seen before include "Map; intention" , "Layout drawing" , "Method laid out for accomplishing something" , "Intention or decision about what one is going to do" , "chart" .)