Record spell of good fortune securing a very small sporting trophy (5,3)
I believe the answer is:
davis cup
'sporting trophy' is the definition.
'record spell of good fortune securing a very small' is the wordplay.
'record' becomes 'disc' ('disc' can be a synonym of 'record').
'spell of good fortune' becomes 'up' (as in ups and downs).
'securing' means one lot of letters goes inside another.
'very small' becomes 'v' (abbreviated or small form of 'very').
'disc'+'up'='discup'
'a'+'v'='av'
'discup' placed around 'av' is 'DAVIS CUP'.
(Other definitions for davis cup that I've seen before include "Annual tennis team championship award" , "event?" , "International tennis competition" , "International tennis tournament" , "International tennis team championship" .)