The most common and most likely answer to this crossword clue is the 11 letter word HOMOGENEOUS
I've seen this crossword clue in The Daily Telegraph
H
O
M
O
G
E
N
E
O
U
S
Buddy explains!

The straight part
We know that "of a similar type" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case of a similar type = homogeneous.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 HOMOGENEOUS mean?
HOMOGENEOUS adjective- Of the same kind; alike, similar.
- Having the same composition throughout; of uniform make-up.
- In the same state of matter.
- Of which the properties of a smaller set apply to the whole; scalable.