The most common and most likely answer to this crossword clue is the 7 letter word TURTLES
T
U
R
T
L
E
S
More clues leading to the result TURTLES
Buddy explains!

The straight part
We know that "reptiles" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case reptiles = turtles.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 TURTLES mean?
TURTLES noun- Any land or marine reptile of the order Testudines, characterised by a protective shell enclosing its body. See also tortoise.
- (specifically) A marine reptile of that order.
- An Ancient Roman attack method, where the shields held by the soldiers hide them, not only left, right, front and back, but also from above.
- A type of robot having a domed case (and so resembling the reptile), used in education, especially for making line drawings by means of a computer program.
- An on-screen cursor that serves the same function as a turtle for drawing.
- The curved plate in which the form is held in a type-revolving cylinder press.
- A small element towards the end of a list of items to be bubble sorted, and thus tending to take a long time to be swapped into its correct position. Compare rabbit.
- A breakdancing move consisting of a float during which the dancer's weight shifts from one hand to the other, producing rotation or a circular "walk".
- A low stand for a lamp etc.
- To flip over onto the back or top; to turn upside down.
- To turn and swim upside down.
- To hunt turtles, especially in the water.
- To build up a large defense force and strike only punctually, rather than going for an offensive strategy.
- A turtle dove.