Ripple disturbed twelve outside space centre (7)

'ripple' is the definition.
(I know that ripple can be written as wavelet)

'disturbed twelve outside space centre' is the wordplay.
'disturbed' indicates an anagram (the order of letters is disturbed).
'outside' means one lot of letters goes inside another (some letters go outside others).
'centre' indicates the central letters.
The centre of 'space' is 'a'.
'twelve' anagrammed gives 'wvelet'.
'wvelet' enclosing 'a' is 'WAVELET'.