Satisfy number held in Tory grip (8)
I believe the answer is:
convince
'satisfy' is the definition.
(I've seen this before)
'number held in tory grip' is the wordplay.
'number' becomes 'n' (n can represent any number).
'held in' means one lot of letters goes inside another.
'tory' becomes 'con' (abbreviation for Conservative).
'grip' becomes 'vice' (I've seen this before).
'con'+'vice'='convice'
'n' put inside 'convice' is 'CONVINCE'.
(Other definitions for convince that I've seen before include "Persuade someone of the truth of something" , "Satisfy by evidence" , "Make believe" , "Bring round" , "Be persuasive" .)