Thanks fellow has accepted (5)
I believe the answer is:
taken
'accepted' is the definition.
(taking is a kind of accepting)
'thanks fellow' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'fellow' becomes 'ken' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ta'+'ken'='TAKEN'
'has' is the link.
Can you help me to learn more?
(Other definitions for taken that I've seen before include "Removed, accepted" , "This is spoken for" , "Appropriated" , "Transported" , "Kidnapped" .)