Best man turned up in warehouse (5)
I believe the answer is:
depot
'warehouse' is the definition.
(I've seen this before)
'best man turned up' is the wordplay.
'best' becomes 'top' (top can mean the very best).
'man' becomes 'Ed' (short for Edward).
'turned up' is a reversal indicator.
'top'+'ed'='toped'
'toped' backwards is 'DEPOT'.
'in' is the link.
(Other definitions for depot that I've seen before include "Opted (anag)" , "Terminus for transport vehicles" , "Place where buses and trains are kept" , "storeroom" , "Bus station in the US" .)