The most common and most likely answer to this crossword clue is the 11 letter word FLIRTATIOUS
I've seen this crossword clue in Independent
F
L
I
R
T
A
T
I
O
U
S
Buddy explains!

The straight part
We know that "typical of one making advances" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case typical of one making advances = flirtatious.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 FLIRTATIOUS mean?
FLIRTATIOUS adjective- Of or pertaining to flirtation.
- (of a person) Having a tendency to flirt often.