Soft rock ultimately improves pensioner's mood (9)
I believe the answer is:
soapstone
'soft rock' is the definition.
'soapstone' can be an answer for 'rock' (soapstone is a kind of rock). I'm not sure about the 'soft' bit.
'ultimately improves pensioner's mood' is the wordplay.
'ultimately' indicates one should take the final letters.
'pensioner's' becomes 'OAP's' (old age pensioner).
'mood' becomes 'tone' (tone is a kind of mood).
The last letter of 'improves' is 's'.
's'+'oaps'+'tone'='SOAPSTONE'
Can you help me to learn more?
(Other definitions for soapstone that I've seen before include "Soft type of rock" , "Soft talcy rock" , "Soft form of rock" , "Compact variety of talc - teaspoons (anag)" , "Soft steatitic rock" .)