Calculate that passing through valley will raise their spirits (7)
I believe the answer is:
gladden
'raise their spirits' is the definition.
I can't judge whether this definition defines the answer.
'calculate that passing through valley' is the wordplay.
'calculate' becomes 'add' (adding is a kind of calculating).
'that passing through' indicates putting letters inside.
'valley' becomes 'glen' (glen is a kind of valley).
'add' put into 'glen' is 'GLADDEN'.
'will' acts as a link.
Can you help me to learn more?
(Other definitions for gladden that I've seen before include "Make joyful" , "Lift (the heart)" , "Give pleasure to" , "Fill with joy" , "please" .)