Compatible with Irishman (3)
I believe the answer is:
pat
'irishman' is the definition.
(Patrick is a common Irish name)
'compatible with' is the wordplay.
'with' says the answer is hidden in the clue.
'PAT' is hidden in the letters of 'compatible'.
(Other definitions for pat that I've seen before include "Portion of butter" , "Touch gently; glib" , "Girl" , "Affectionate gesture - postman" , "Touch with hand" .)