Step welcomed by wise contemporary (5-3)
I believe the answer is:
space-age
'contemporary' is the definition.
'step welcomed by wise' is the wordplay.
'step' becomes 'pace' (pace is a kind of step).
'welcomed by' means one lot of letters goes inside another (letters welcomed inside).
'wise' becomes 'sage' (similar in meaning).
'pace' going within 'sage' is 'SPACE-AGE'.
(Other definitions for space-age that I've seen before include "Ultra-modern" , "Futuristic" .)