Shrublands have suffered, primarily after hot weather (6)
I believe the answer is:
heaths
'shrublands' is the definition.
(I've seen this in another clue)
'have suffered primarily after hot weather' is the wordplay.
'primarily' says to take the initial letters.
'after' means one lot of letters go next to another.
'hot weather' becomes 'heat'.
The first letters of 'have suffered' is 'hs'.
'hs' after 'heat' is 'HEATHS'.
(Other definitions for heaths that I've seen before include "Moors" , "Sandy areas; shrubs" , "Moorlands" , "Tracts of wasteland with scrubby vegetation" .)