For a second, perhaps, it's different (5)
I believe the answer is:
other
This clue is a double definition.
'for a second' is the first definition.
(I've seen this before)
'it's different' is the second definition.
(similar in meaning)
'perhaps' acts as a link.
(Other definitions for other that I've seen before include "Different; alternate" , "Different (from those mentioned)" , "Alternative of two" , "Not the one mentioned" , "Alternate; additional" .)