Turning up, bumped into one couple (4)
I believe the answer is:
item
'couple' is the definition.
(I've seen this before)
'turning up bumped into one' is the wordplay.
'turning up' says the letters should be written backwards.
'bumped into' becomes 'met' (I've seen this before).
'one' becomes 'i' (Roman numeral).
'met'+'i'='meti'
'meti' in reverse letter order is 'ITEM'.
(Other definitions for item that I've seen before include "Boyfriend and girlfriend" , "Two people romantically linked" , "Syrian capital" , "Individual unit in a list" , "section of magazine" .)