Figure? A month, then endless intense suffering (7)
I believe the answer is:
octagon
'figure?' is the definition.
(octagon is a kind of figure)
'a month then endless intense suffering' is the wordplay.
'a month' becomes 'Oct' (abbreviation for October).
'then' means one lot of letters go next to another.
'endless' means to remove the last letter.
'intense suffering' becomes 'agony' (I've seen this in another clue).
'agony' with its last letter taken off is 'agon'.
'oct'+'agon'='OCTAGON'
(Other definitions for octagon that I've seen before include "Eight-sided shape" , "plane figure" , "An eight-sided polygon" , "Figure with 8 sides" , "Geometric figure with eight sides" .)