The most common and most likely answer to this crossword clue is the 7 letter word STOICAL
I've seen this crossword clue in The Times
S
T
O
I
C
A
L
More clues leading to the result STOICAL
- After treatment, lots going about in charge of a patient
- Social Democrat in the end, unfortunately, resigned
- Society of current importance, stripped of power, but not complaining
- Job was such special work involving chief accountant
- Clio sat composed and uncomplaining
- Clio sat composed and resigned
- Specialist’s first work containing account about patient
- Measure short nurses for one patient
- Long-suffering patient, uncomplaining
- I lost a staggering figure – that’s accepted, uncomplaining
Buddy explains!

The straight part
We know that "but not complaining" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case but not complaining = stoical.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 STOICAL mean?
STOICAL adjective- Enduring pain and hardship without showing feeling or complaint.