Don't have stabilisers, which does surprise you (4)

I believe the answer is:

rock

I'm a little stuck... Click here to teach me more about this clue!

'surprise you' is the definition.
'rock' can be an answer for 'surprise' (thesaurus). I am not certain of the 'you' bit.

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for rock that I've seen before include "Music; diamond" , "Hard confectionery made in sticks" , "musical genre?" , "Modern music with a heavy beat" , "Edinburgh - -" .)

I've seen this clue in the Evening Standard.

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