Supposed average time (5)
I believe the answer is:
meant
'supposed' is the definition.
(thesaurus)
'average time' is the wordplay.
'average' becomes 'mean' (type of average).
'time' becomes 't'.
'mean'+'t'='MEANT'
(Other definitions for meant that I've seen before include "Signified" , "planned" , "Intentional" , "proposed" , "intimated" .)