Finish phoning with some difficulty (4,2)
I believe the answer is:
hang up
'difficulty' is the definition.
(thesaurus)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for hang up that I've seen before include "Put the phone down" , "Close call" , "that makes one stop talking" , "Replace receiver" , "An emotional problem or inhibition (4-2)" .)