Is to prosecute in spring (5)
I believe the answer is:
'spring' is the definition.
'is to prosecute' is the wordplay.
'to prosecute' becomes 'sue' (I've seen this in another clue).
'in' is the link.
(Other definitions for issue that I've seen before include "Publish; children" , "litter" , "Matter of contention" , "Susie (anag.)" , "Circulate, distribute or equip with" .)