Humorist is better having small heart (7)
I believe the answer is:
punster
'humorist' is the definition.
(I know that punster is a type of humorist)
'is better having small heart' is the wordplay.
'is better' becomes 'punter' (I've seen this before).
'having small' becomes 's' (I can't justify this - if you can you should believe this answer much more).
'heart' is an insertion indicator.
'punter' placed around 's' is 'PUNSTER'.
Can you help me to learn more?
(Other definitions for punster that I've seen before include "Verbal joker" , "Comedian" , "user of wordplay" , "One playing on words" , "One who plays on words" .)