Leave old computer equipment (4)
I believe the answer is:
exit
'leave' is the definition.
(synonyms)
'old computer equipment' is the wordplay.
'old' becomes 'ex'.
'computer equipment' becomes 'it' (abbreviation for Information Technology).
'ex'+'it'='EXIT'
(Other definitions for exit that I've seen before include "Depart" , "Sudden rush of pleasure" , "Withdrawal" , "Leave the stage" , "Outlet" .)