Inclination to knock quietly (4)
I believe the answer is:
ramp
'inclination' is the definition.
(an inclined surface)
'knock quietly' is the wordplay.
'knock' becomes 'ram' (I am not sure about this - if you are sure you should believe this answer much more).
'quietly' becomes 'p' (musical symbol).
'ram'+'p'='RAMP'
'to' is the link.
Can you help me to learn more?
(Other definitions for ramp that I've seen before include "Level-connecting slope" , "Slope for a pram" , "Smoothed-out stairs" , "Sloping walkway" , "Inclined plane; swindle" .)