The most common and most likely answer to this crossword clue is the 9 letter word TENDERISE
I've seen this crossword clue in Financial Times
T
E
N
D
E
R
I
S
E
More clues leading to the result TENDERISE
- I resented being forced to soften up
- Soften mood finally during rite seen as grotesque
- Soften up last pair of climate change deniers
- Proposal getting viewers, reportedly, to soften
- Some East-ender is eating mash?
- Make soft cooked entrees — idlis, dosas primarily
- Doctor inserted syringe's tip to have softening effect
- Submission issuer occasionally supports to soften things up
Buddy explains!

The straight part
We know that "to soften up" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case to soften up = tenderise.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 TENDERISE mean?
TENDERISE verb- To make (something, especially meat) tender.