The most common and most likely answer to this crossword clue is the 8 letter word SOCIABLE
I've seen this crossword clue in The Daily Telegraph
S
O
C
I
A
B
L
E
More clues leading to the result SOCIABLE
- Friendly lad displacing new guy to embrace one
- Friendly agents book in alone
- Matey only accommodating one in taxi
- Chatty note I put in message
- Friendly Society getting one capable of doing things
- Warm trio of islands to the west
- Thus one in chain possibly is fond of others’ company
- Friendly Society, one having what it takes
- Thus guy embracing one, getting friendly …
- ... therefore, wire carrying current becomes warm
Buddy explains!

The straight part
We know that "Warm" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case warm = sociable.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does SOCIABLE mean?
SOCIABLE noun- A sociable person.
- A four-wheeled open carriage with seats facing each other.
- A tricycle for two persons side by side.
- A couch with a curved S-shaped back.
- An informal party or church meeting for purposes of socializing.
- (of a person) Tending to socialize or be social
- Offering opportunities for conversation; characterized by much conversation.
- Capable of being, or fit to be, united in one body or company; associable.
- No longer hostile; friendly.