The most common and most likely answer to this crossword clue is the 4 letter word WARM
I've seen this crossword clue in The Times
W
A
R
M
More clues leading to the result WARM
- Cordial, neither hot nor cold
- Maiden inexperienced becomes upset, tender
- Lively group of workers head off
- Friendly with member
- Month gets cold and damp, needing to turn up heat
- Affectionate wife joining member
- Close hostilities with ultimatum, finally
- Friendly, wife with member
- Friendly, minutes after fighting
- Kind with gun?
Buddy explains!

The straight part
We know that "tender" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tender = warm.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 WARM mean?
WARM adjective- Having a temperature slightly higher than usual, but still pleasant; mildly hot.
- Caring and friendly, of relations to another person.
- Having a color in the red-orange-yellow part of the visible electromagnetic spectrum.
- Close, often used in the context of a game in which "warm" and "cold" are used to indicate nearness to the goal.
- Fresh, of a scent; still able to be traced.
- Communicating a sense of comfort, ease, or pleasantness
- Ardent, zealous.
- Well off as to property, or in good circumstances; rich.
- Requiring arduous effort.
- The act of warming, or the state of being warmed; a heating.
- To make or keep warm.
- To become warm, to heat up.
- To favour increasingly.
- To become ardent or animated.
- To make engaged or earnest; to interest; to engage; to excite ardor or zeal in; to enliven.
- To beat or spank.