Step up, for a bit of fear is erotic (5)
I believe the answer is:
riser
'step up' is the definition.
(I've seen this before)
'a bit of fear is erotic' is the wordplay.
'a bit of' indicates the answer is hidden within the clue (I've seen 'a bit' mean this (the answer is formed by a bit of the clue)).
'RISER' is hidden within 'fear is erotic'.
'for' is the link.
(Other definitions for riser that I've seen before include "Face of a step" , "I get up" , "One who has stopped sleeping" , "found on the staircase" , "Person getting out of bed" .)