The most common and most likely answer to this crossword clue is the 4 plus 5 letter word DECK CHAIR
I've seen this crossword clue in The Times
D
E
C
K
C
H
A
I
R
More clues leading to the result DECK CHAIR
Buddy explains!
The straight part
We know that "seat outdoors" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case seat outdoors = deck chair.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 DECK CHAIR mean?
DECK CHAIR noun- A folding chair in which a wooden frame supports a length of canvas; traditionally used on the beach or onboard a liner.