Countries seen in April and September (5)
I believe the answer is:
lands
'countries' is the definition.
(I know this)
'in april and september' is the wordplay.
'in' indicates a hidden word.
'LANDS' can be found hidden inside 'april and september'.
'seen' is the link.
(Other definitions for lands that I've seen before include "See 21" , "Obtains" , "Comes ashore" , "Alights" .)