Three successive characters, having fish, pay (6)
I believe the answer is:
defray
'pay' is the definition.
(I know that defray is a more specific form of pay)
'three successive characters having fish' is the wordplay.
'three successive characters' becomes 'def' (I can't justify this - if you can you should give a lot more credence to this answer).
'having' says to put letters next to each other.
'fish' becomes 'ray' (ray is a kind of fish).
'def'+'ray'='DEFRAY'
Can you help me to learn more?
(Other definitions for defray that I've seen before include "Cover (financially)" , "Meet the costs of" , "Cover the cost of" , "clear" , "Bear the expenses of" .)