The most common and most likely answer to this crossword clue is the 9 letter word TITILLATE
I've seen this crossword clue in The Guardian
T
I
T
I
L
L
A
T
E
More clues leading to the result TITILLATE
- Stimulate sensually, keeping it up well into the night
- Tickle bird, badly worried
- I work in gallery providing thrill
- Tickle a little drunk with it
- Thrill seeing ultimate in prize, unlikely it doubled up
- Shake it a little to create excitement
- Excite poorly-fed bird first
- Tickle and excite it a little
- Arouse by wiggling it a little
- Tickle bird, poorly fed
Buddy explains!

The straight part
We know that "Tickle/Tickle" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tickle/tickle = titillate.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 TITILLATE mean?
TITILLATE verb- To stimulate or excite sensually