Universal time in fluid motion - true (7)
I believe the answer is:
dutiful
'true' is the definition.
(thesaurus)
'universal time in fluid motion' is the wordplay.
'universal' becomes 'U' (film certificate).
'time' becomes 't' (abbreviation).
'in' indicates putting letters inside.
'motion' indicates an anagram.
'u'+'t'='ut'
'fluid' with letters rearranged gives 'diful'.
'ut' put into 'diful' is 'DUTIFUL'.
(Other definitions for dutiful that I've seen before include "Being what England expected" , "Compliant, obedient" , "Doing what one should" , "Punctilious" , "to be working properly?" .)