Extensive international lying not admitting of remedy (9)
I believe the answer is:
capacious
'extensive' is the definition.
(I've seen this before)
'international lying not admitting of remedy' is the wordplay.
'international' becomes 'cap' (sportsperson who competes internationally).
'lying' becomes 'mendacious' (synonyms).
'not admitting of' is a deletion indicator (to admit is to allow in).
'remedy' becomes 'mend' (both can mean to fix or address).
'mendacious' with 'mend' removed is 'acious'.
'cap'+'acious'='CAPACIOUS'
(Other definitions for capacious that I've seen before include "Extensive" , "Big" , "Voluminous" , "Commodious" , "Roomy" .)