Weird at all times, that is (5)
I believe the answer is:
eerie
'weird' is the definition.
(thesaurus)
'at all times that is' is the wordplay.
'at all times' becomes 'eer' ('e'er' can be a synonym of 'at all times').
'that is' becomes 'ie' ('i.e.' can be a synonym of 'that is').
'eer'+'ie'='EERIE'
(Other definitions for eerie that I've seen before include "Spooky, creepy" , "Sinister" , "Spectral" , "Spooky, macabre" , "Uncannily strange" .)