Trend of current ideology (4)
I believe the answer is:
tide
'trend' is the definition.
(thesaurus)
'of current ideology' is the wordplay.
'of' indicates a hidden word.
'TIDE' is hidden within 'current ideology'.
(Other definitions for tide that I've seen before include "Ebber and flower?" , "Season; current" , "Surge of events" , "One thing that waits for no man" , "Something going in and out" .)