Turn trophy around four (5)
I believe the answer is:
pivot
'turn' is the definition.
(pivoting is a kind of turning)
'trophy around four' is the wordplay.
'trophy' becomes 'pot' (type of trophy).
'around' means one lot of letters goes inside another.
'four' becomes 'IV' (Roman numerals).
'pot' enclosing 'iv' is 'PIVOT'.
(Other definitions for pivot that I've seen before include "On which one turns" , "Point of rotation" , "Centre point" , "Central turning point" , "Turning pin" .)