Time's against goddess (5)
I believe the answer is:
erato
'goddess' is the definition.
(I've seen this before)
'time's against' is the wordplay.
'time' becomes 'era' (an era is a period of time).
'against' becomes 'to' (as in a lean-to, building leaning against anothe).
'era'+'to'='ERATO'
(Other definitions for erato that I've seen before include "poetic patroness" , "Arts patron" , "Poet's inspiration" , "Muse of lyric love-poetry" , "Source of artistic inspiration" .)