Make love legible in letters from the heart (6)
I believe the answer is:
oblige
'make' is the definition.
(obliging is a kind of making)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for oblige that I've seen before include "Compel (someone to do something)" , "serve" , "Put oneself out for" , "Hold in debt" , "Do favour or coerce" .)