Lidl's opening provided swell launch (4-3)
I believe the answer is:
lift-off
'launch' is the definition.
(I've seen this before)
'lidl's opening provided swell' is the wordplay.
'opening' indicates taking the first letters.
'provided' becomes 'if' (eg 'provided it's sunny' means 'if it's sunny').
'swell' becomes 'toff' (wealthy or high-class person).
The first letter of 'lidl' is 'l'.
'l'+'if'+'toff'='LIFT-OFF'
(Other definitions for lift-off that I've seen before include "Start of rocket's journey" , "Launch (of rocket)" , "Moment of rocket's launch" , "Instant when rocket leaves launching pad" .)