Seating broken by second very large lady (8)
I believe the answer is:
giantess
'very large lady' is the definition.
'seating broken by second' is the wordplay.
'broken' indicates anagramming the letters.
'by' is a charade indicator (letters next to each other).
'second' becomes 's' (common abbreviation**).
'seating' with letters rearranged gives 'giantes'.
'giantes'+'s'='GIANTESS'
(Other definitions for giantess that I've seen before include "Very large female" , "Big woman" .)