The answer will depend on being soft-hearted (5)
I believe the answer is:
reply
'the answer' is the definition.
('reply' can be a synonym of 'answer')
'depend on being soft-hearted' is the wordplay.
'depend' becomes 'rely' (I've seen this before).
'on' indicates putting letters inside (as in clothing \'on\' a person).
'being soft-hearted' becomes 'p' (I can't explain this - if you can you should believe this answer much more).
'rely' going around 'p' is 'REPLY'.
'will' is the link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for reply that I've seen before include "counterattack?" , "Reciprocate" , "Return" , "Comeback" , "Counter" .)