Be totally persuasive so as to trick a fellow (8)
I believe the answer is:
convince
'be totally persuasive so as' is the definition.
I can't tell whether this definition defines the answer.
'trick a fellow' is the wordplay.
'trick' becomes 'con' (a con is a fraud or trick).
'a fellow' becomes 'vince' (I can't justify this - if you can you should give a lot more credence to this answer).
'con'+'vince'='CONVINCE'
'to' is the link.
Can you help me to learn more?
(Other definitions for convince that I've seen before include "Satisfy by evidence" , "Be persuasive" , "Win over to your point of view" , "Satisfy as to truth" , "Make believe" .)