A letter from Paul to a sweetheart is a warming thing (8)
I believe the answer is:
pullover
'a warming thing' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?
'a letter from paul to a sweetheart' is the wordplay.
'a letter' becomes 'a'.
'from' indicates named letters should be taken away.
'to a sweetheart' becomes 'lover' (sweetheart can mean a lover).
'paul' with 'a' removed is 'pul'.
'pul'+'lover'='PULLOVER'
'is' is the link.
Can you help me to learn more?
(Other definitions for pullover that I've seen before include "Woolly" , "top gear?" , "Go to side of road" , "Jersey" , "Knitted garment" .)