It's worth making an about-turn in the valley (5)
I believe the answer is:
value
'it's worth' is the definition.
(value is a kind of worth)
'an about-turn in the valley' is the wordplay.
'an about turn' becomes 'u' (a 'U-turn' is a kind of turn. I am not sure about the 'about' bit.**).
'in the' indicates putting letters inside.
'valley' becomes 'vale' ('vale' can be a synonym of 'valley').
'u' going into 'vale' is 'VALUE'.
'making' is the link.
Can you help me to learn more?
(Other definitions for value that I've seen before include "Intrinsic goodness" , "Worth or importance of something" , "Consider to be important" , "Estimate the worth of" , "Importance, worth or usefulness" .)