Wonder regatta week contains (3)
I believe the answer is:
awe
'wonder' is the definition.
(awe is a kind of wonder)
'regatta week contains' is the wordplay.
'contains' indicates the answer is hidden within the clue.
'AWE' can be found hidden inside 'regatta week'.
(Other definitions for awe that I've seen before include "Reverential wonder" , "Wonderment" , "Fear - veneration" , "Great wonder" , "Wide-eyed wonder" .)