Ice vat unfortunately occupied (6)
I believe the answer is:
active
'occupied' is the definition.
(thesaurus)
'ice vat unfortunately' is the wordplay.
'unfortunately' is an anagram indicator (a bad or unfortunate spelling).
'ice'+'vat'='icevat'
'icevat' anagrammed gives 'ACTIVE'.
(Other definitions for active that I've seen before include "Vigorously moving" , "On the go" , "(Of mind) alert, lively" , "Moving, doing things" , "Working; moving" .)