Begin quietly then grow readiness for undertaking (10)
I believe the answer is:
enterprise
'undertaking' is the definition.
(enterprise is a kind of undertaking)
'begin quietly then grow readiness' is the wordplay.
I cannot quite see how this works, but
'quietly' could be 'p' (p for piano and quiet) and 'p' is found in the answer.
'grow' could be 'rise' (rising is a kind of growing) and 'rise' is found in the answer.
The remaining letters 'enter' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'for' is the link.
Can you help me to learn more?
(Other definitions for enterprise that I've seen before include "Plan" , "Company" , "Initiative - undertaking - business" , "audacity" , "Data may be on-board here" .)