Bolt loosened for fun (3,3)
I believe the answer is:
run off
'bolt' is the definition.
(I know that bolt can be written as run off)
'loosened for fun' is the wordplay.
'loosened' is an anagram indicator.
'for'+'fun'='forfun'
'forfun' anagrammed gives 'RUN-OFF'.
(Other definitions for run off that I've seen before include "Escape" , "Further contest; drainage" , "exit at speed" , "Drain" , "Make copies" .)