Working in Perth, wanted to celebrate uninhibitedly (5,3,4,3)
I believe the answer is:
paint the town red
'celebrate uninhibitedly' is the definition.
'working in perth wanted to' is the wordplay.
'working' indicates an anagram.
'in'+'perth'+'wanted'+'to'='inperthwantedto'
'inperthwantedto' anagrammed gives 'PAINT THE TOWN RED'.
(Other definitions for paint the town red that I've seen before include "get rid of the blues?" , "Go on a pub crawl" , "Celebrate" , "enjoy celebration" .)