The most common and most likely answer to this crossword clue is the 6 plus 8 letter word POUNDS STERLING
I've seen this crossword clue in The Guardian
P
O
U
N
D
S
S
T
E
R
L
I
N
G
More clues leading to the result POUNDS STERLING
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 = pounds sterling.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.