Record Irishman coming up on Ecstasy (4)
I believe the answer is:
tape
'record' is the definition.
('tape' can be a synonym of 'record')
'irishman coming up on ecstasy' is the wordplay.
'irishman' becomes 'pat'.
'coming up' shows that the letters should be reversed in order.
'on' says to put letters next to each other.
'ecstasy' becomes 'e' (informal term for the drug).
'pat' written backwards gives 'tap'.
'tap'+'e'='TAPE'
(Other definitions for tape that I've seen before include "Music cassette" , "Ribbon" , "Sticky strip" , "Binder" , "Race finishing line strip" .)