Warmth of soft drink - pity it doesn't start! (10)
I believe the answer is:
cordiality
'warmth' is the definition.
(I've seen this before)
'soft drink pity it doesn't start' is the wordplay.
I cannot quite understand how this works, but
'drink' could be 'cordial' (cordial is a kind of drink) and 'cordial' is located in the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is located in the answer.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Another definition for cordiality that I've seen is " Warmth".)