Endless crush preceding time signal (7)
I believe the answer is:
presage
'signal' is the definition.
(presage is a kind of signal)
'endless crush preceding time' is the wordplay.
'endless' means to remove the last letter.
'crush' becomes 'press' (synonyms).
'preceding time' becomes 'age' (an age is a period of time. I am not sure about the 'preceding' bit.).
'press' with its final letter removed is 'pres'.
'pres'+'age'='PRESAGE'
Can you help me to learn more?
(Other definitions for presage that I've seen before include "Be a sign or warning of (an event)" , "Be an advance sign of, portend" , "Be a sign of (something)" , "Forecast, foreshadow" , "Portent" .)