Main issue in spring, for example (6)
I believe the answer is:
season
'spring for example' is the definition.
(spring is a kind of season)
'main issue' is the wordplay.
'main' becomes 'sea' (the main is an old name for the sea).
'issue' becomes 'son' (issue can mean someone's offspring).
'sea'+'son'='SEASON'
'in' acts as a link.
(Other definitions for season that I've seen before include "To dry (wood) for use as timber" , "Add condiments to for time of year" , "' - - of mists ...' (Keats)" , "Salt, maybe" , "eg.Summer" .)