Nothing the same -- it must be spring (5)
I believe the answer is:
oasis
'spring' is the definition.
(I've seen this before)
'nothing the same' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'the same' becomes 'as is' (I've seen this before).
'o'+'asis'='OASIS'
'it must be' is the link.
(Other definitions for oasis that I've seen before include "place of refuge" , "beauty spot" , "Noel & Liam's band" , "flower arranging stuff" , "Famous group" .)