Step to portal, say (4)
I believe the answer is:
gait
'step' is the definition.
(I've seen this in another clue)
'portal say' is the wordplay.
'portal' becomes 'gate' (I've seen this before).
'say' shows a homophone (sound like).
'gate' sounds like 'GAIT'.
'to' is the link.
(Other definitions for gait that I've seen before include "walkway?" , "Manner of walking or running" , "Style of movement" , "Deportment" , "Way of walking (4)" .)