One-one will suit him (3)
I believe the answer is:
ian
'suit him' is the definition.
'Ian' can be an answer for 'him'. I'm not certain of the 'suit' bit.
'one-one' is the wordplay.
'one' becomes 'i' (Roman numeral).
'one' becomes 'an' (an apple is one apple).
'i'+'an'='IAN'
'will' is the link.
Can you help me to learn more?
(Other definitions for ian that I've seen before include "The familar Dr Paisley" , "... Fleming, author of the Bond books" , "Scottish John" , "Scottish man's name" , "- McEwan, Eng. writer" .)